AIRCRAFT ACCIDENT REPORT 1/2007

ACCIDENT INVESTIGATION DIVISION

Civil Aviation Department

Hong Kong

Report on the accident to

Robinson R44 helicopter, B-HJS,
operated by Topjet Aviation Limited at Pak A, Sai Kung, Hong Kong
on 11 June 2005

Hong Kong
In accordance with Annex 13 to the ICAO Convention on International Civil Aviation and the

Hong Kong Civil Aviation (Investigation of Accidents) Regulations, the sole objective of this

investigation is the prevention of aircraft accidents. It is not the purpose of this activity to

apportion blame or liability.

Contents Page

Table of Contents…………………………………………………………………... i

GLOSSARY OF ABBREVIATIONS USED IN THE REPORT…………………... vi

SYNOPSIS…………………………………………………………………………. x

1. FACTUAL INFORMATION…………………………………………………. 1

1.1 History of Flight……………………………………………………. 1

1.2 Injuries to Persons………………………………………………….. 3

1.3 Damage to Aircraft…………………………………………………. 3

1.4 Other Damage……………………………………………………… 3

1.5 Personnel Information……………………………………………… 3

1.6 Aircraft Information………………………………………………... 4

1.6.1 Airworthiness and Maintenance of Aircraft……………... 4

1.6.2 Aircraft Description……………………………………... 6

1.6.3 Performance and Centre of Gravity……………………... 10

1.6.4 Fuel………………………………………………………. 10

1.7 Meteorological Information………………………………………... 10

1.7.1 Weather Forecast and Observations……………………... 10

1.7.2 Meteorological Information Available at the HKAC……. 14

1.7.3 Meteorological Information Obtained by the Pilot……… 14

1.7.4 Pilot’s Assessment of Wind Conditions at Pak A………... 15

1.8 Aids to Navigation…………………………………………………. 15

1.9 Communications…………………………………………………… 16

i
 1.10 Aerodrome Information……………………………………………. 17

1.11 Flight Recorders……………………………………………………. 17

1.12 Wreckage and Impact Information…………………………………. 17

1.13 Medical and Pathological Information……………………………... 19

1.13.1 The Pilot………………………………………………..... 19

1.13.2 Left Front Seat Passenger……………………………...... 20

1.13.3 Left Rear Seat Passenger……………………………........ 20

1.13.4 Right Rear Seat Passenger……………………………..... 20

1.14 Fire…………………………………………………………………. 21

1.15 Survival Aspects……………………………………………………. 21

1.15.1 Search and Rescue……………………………………..... 21

1.15.2 Aircraft Survivability…………………………………..... 21

1.16 Tests and Research…………………………………………………. 22

1.17 Organization and Management Information……………………….. 22

2. ANALYSIS…………………………………………………………………… 23

2.1 Flight Operations and Aircraft Airworthiness……………………… 23

2.1.1 Vibration and Noise……………………………………… 23

2.1.2 Flying Controls…………………………………………... 23

2.1.3 Tail Rotor Blades………………………………………… 26

2.1.4 Tail Rotor Drive Shaft…………………………………… 28

2.1.5 Tail Rotor Control System………………………………. 28

2.1.6 Contact with Foreign Objects…………………………… 29

ii
 2.1.7 Hydraulic Pump, Right Magneto, Governor Controller

and Governor Motor……………………………………... 29

2.1.8 Surface Wind Conditions and Topographic Effects at Pak

A………………………………………………………… 29

2.1.9 Aerodynamic Effects on Tail Rotor……………………... 32

2.2 Meteorology………………………………………………………... 46

2.3 Communications and Navigation Aids……………………….......... 48

2.4 Aircraft Survivability………………………………………………. 48

2.5 Air Traffic Service………………………………………………….. 53

2.6 Emergency and Rescue Services…………………………………… 53

3. CONCLUSIONS……………………………………………………………… 54

3.1 Findings…………………………………………………………….. 54

3.2 Cause……………………………………………………………….. 57

3.3 Contributing Factors……………………………………………….. 58

4. SAFETY RECOMMENDATIONS…………………………………………… 59

4.1 Recommendation 2007-1...………………………………………… 59

4.2 Recommendation 2007-2…………………………………………... 59

iii
5. PHOTOGRAPHS, MAP, FIGURES AND APPENDICES

Photograph 1 Helicopter Lift-Off and Wreckage Positions at Pak

A……………………………………………………. 2

Photograph 2 Helicopter Wreckage……………………………….. 18

Photograph 3 Governor Switch at ‘OFF’ Position………………… 24

Photograph 4 Tail Rotor Hub and Broken Blade………………….. 26

Photograph 5 Search Area for Missing Part of Broken Tail Rotor

Blade……………………………………………….. 27

Photograph 6a Broken End of Tail Rotor Drive Shaft……………... 28

Photograph 6b The Other Broken End of Tail Rotor Drive Shaft….. 28

Photograph 7 Topography at Pak A……………………………….. 31

Photograph 8 Deformation of the Left Underside of the Fuselage

due to the Accident.………………………………… 49

Map 1 Geographical Location of Pak A…………………… 30

Figure 1 Anti-Torque Effect and Tail Rotor Thrust………….. 34

Figure 2 Induced Flow and Tail Rotor Thrust……………….. 35

Figure 3 Induced Flow and Rate of Turn Flow during the

Yaw Turn…………………………………………… 36

Figure 4 Aerodynamic Relationship between Induced Flow

and Lift……………………………………………... 37

Figure 5 Hovering Tailwind with a High All Up Weight……. 37

Figure 6 Application of Right Yaw Pedal to Turn Right…….. 39

iv
Figure 7 Wind from 3 o’clock Position………………….…... 41

Figure 8 Helicopter Facing the Wind….………………….…. 43

Figure 9 Tail Rotor Stall……………………………………... 44

Figure 10 Left Drift of the Helicopter due to Loss of Tail

Rotor Thrust………………………………………... 46

Appendix A Simplified Schematic Diagram of the Powerplant

and Transmission System of R44 Helicopter………. 61

Appendix B Location of Pak A, Sai Kung in UCARA………….. 63

Appendix C Damage to the Helicopter……………………..……. 65

Appendix D Summary of Emergency Handling of the Helicopter

Accident on 11 June 2005………………………….. 67

Appendix E Letter Issued by CAD in January 2004 on UKCAA

Flight Operations Department Communication

1/2004………………………………………………. 75

Appendix F Emergency Procedures for Loss of Tail Rotor Thrust

during Hover……………………………………….. 79

v
GLOSSARY OF ABBREVIATIONS USED IN THE REPORT

ATS Air Traffic Service

CAD Civil Aviation Department Hong Kong

cm Centimetre
o
C Degree Celsius
o
Degree

FAR Federal Aviation Regulations, the United States

FIS Flight Information Service

FSCC Fire Services Communication Centre (FSD)

FSD Fire Services Department

g Acceleration due to Gravity

GFS Government Flying Service

IF Induced Flow

HKAC Hong Kong Aviation Club Limited

HKO Hong Kong Observatory

HKP Hong Kong Police

hrs Hours

km Kilometre

knots Nautical Miles Per Hour

lb Pound

LTE Loss of Tail Rotor Effectiveness

LTT Loss of Tail Rotor Thrust

METAR Aerodrome Routine Meteorological Report

MHz Megahertz

vi
m Metre

NTSB National Transportation Safety Board, the United States

POH Pilot’s Operating Handbook

POR Plane of Rotation

RAF Relative Air Flow

RCCC/K Kowloon Regional Command & Control Centre (HKP)

RCCC/M Marine Regional Command & Control Centre (HKP)

RPM Revolutions per minute

SAR Search and Rescue

UCARA Uncontrolled Airspace Reporting Areas

UKCAA United Kingdom Civil Aviation Authority

UTC Universal Co-ordinated Time

VFR Visual Flight Rules

VHF Very High Frequency

α Angle between the Relative Air Flow and the Chord of the Rotor Blades

β Angle between the Tail Rotor Blades and the Plane of Rotation

vii
Intentionally Left Blank

viii
 ACCIDENT INVESTIGATION DIVISION

CIVIL AVIATION DEPARTMENT

Aircraft Accident Report 1/2007

Registered Owner: Topjet Aviation Limited

Operator: Topjet Aviation Limited

Aircraft Type: Robinson Helicopter Company R44 Helicopter

Nationality / Registration: B-HJS

Place of Accident: Pak A, Sai Kung, Hong Kong

Latitude: 22º 21.3' N

Longitude: 114º 21.1' E

Date and Time: 11 June 2005 at 0612 hrs (1412 hrs)

All times in this Report are in Universal Co-ordinated Time

(UTC) with Hong Kong Local Time in parenthesis

ix
SYNOPSIS

In the afternoon of 11 June 2005, a Robinson R44 helicopter of Topjet Aviation

Limited operated by a pilot with three passengers on board took off at 0610 hrs (1410

hrs) on a private Visual Flight Rules flight from Pak A to the Hong Kong Aviation

Club at the former Kai Tak Airport.

Whilst the pilot was executing a spot turn to the right after lift-off, the helicopter

yawed continuously to the right, drifting to the left until it impacted with the ground

on a southerly heading at approximately 10 m to the northeast of the lift-off position.

The helicopter then came to rest on its left side. The left skid was substantially

damaged. The main rotor blades remained attached to the helicopter but were

significantly bent and twisted. Both blades of the tail rotor were severed. The tail

boom was severely fractured, locally twisted and bent to the starboard near the tail

rotor drive shaft damper bearing. There was no post-impact fire. The pilot and two

passengers of the helicopter were injured. The first emergency service unit, a

Government Flying Service helicopter, arrived at the scene at approximately 0632 hrs

(1432 hrs) to commence the airlifting of the injured persons to hospital and the last

injured person was airlifted from the scene at 0741 hrs (1541 hrs).

Upon receipt of the notification of the accident from the duty Aerodrome Supervisor

at the Hong Kong International Airport, a team of CAD Inspectors of Accidents

arrived at the scene at approximately 0919 hrs (1719 hrs) to conduct a site appraisal

and survey. The team then carried out a preliminary inspection of the wreckage

including the collection of evidence. The Chief Inspector of Accidents subsequently

ordered an Inspector’s Investigation into the accident in accordance with the Hong

x
Kong Civil Aviation (Investigation of Accidents) Regulations. The sole objective of

this investigation is the prevention of aircraft accidents. It is not the purpose of this

activity to apportion blame or liability.

The investigation concluded that the helicopter experienced, during a yaw turn to the

right after lift-off, a loss of tail rotor effectiveness that led to the stalling of the tail

rotor. Two safety recommendations have been made.

xi
Intentionally Left Blank

xii
1. FACTUAL INFORMATION

1.1 History of Flight

1.1.1 On 11 June 2005, a Robinson R44 helicopter, Registration B-HJS, of Topjet

Aviation Limited fitted with single controls, was operated by a pilot on a

series of private flights under Visual Flight Rules (VFR) between the Hong

Kong Aviation Club Limited (HKAC) at the former Kai Tak Airport and Pak

A near the High Island Reservoir at Sai Kung. The pilot had conducted

two flights into Pak A earlier in the morning, each with three passengers on

board.

1.1.2 After lunch at Pak A, the pilot intended to operate two runs out of Pak A to

transport all passengers back to the HKAC. The first run with three

passengers on board took place uneventfully. The accident occurred

during departure on the second run from Pak A with three passengers on

board. One of the passengers on all these flights was a R44 type rated

helicopter pilot and she had assisted the pilot in escorting the other

passengers into and out of the helicopter. On the accident flight, she

occupied the left rear seat.

1.1.3 The helicopter lifted off at 0610 hrs (1410 hrs) from a sandy-grassed area at

Pak A (see Photograph 1). Whilst the helicopter was in a hover on a

northerly heading, the pilot made a yaw turn to the right with the intention

that the spot turn would stop at 180° (half a revolution) so that the

helicopter could be stabilized in a hover facing the sea before transitioning

1
 to forward flight over the water. This subsequently developed into a

continuous uncontrolled yaw turn, drifting to the left. The helicopter then

impacted with the ground on a southerly heading at approximately 10 m to

the northeast of the lift-off position. The helicopter eventually came to rest

on its left side. The left skid was substantially damaged. The main rotor

blades remained attached to the helicopter but were significantly bent and

twisted. Both blades of the tail rotor were severed. The tail boom was

severely fractured, locally twisted and bent to the starboard near the damper

bearing of the tail rotor drive shaft. There was no post-impact fire.

Lift-Off Position

Wreckage

Photograph 1 Helicopter Lift-Off and Wreckage Positions at Pak A

2
1.2 Injuries to Persons

Injuries Pilot Passenger Total in the helicopter Others

Fatal - - - -

Serious 1 2 3 -

Minor - - - -

None - 1 1 -

Total 1 3 4 -

1.3 Damage to Aircraft

The helicopter was destroyed.

1.4 Other Damage

There was no other damage.

1.5 Personnel Information

Pilot: Male, aged 45 years

Licence: Private Pilot’s Licence (Helicopters)

Aircraft Rating: Robinson R22

Robinson R44

3
 Licensing Flight Test on Type: 4 December 2004

Medical Certificate: Class 2, renewed on 24 March 2005,

valid until 31 March 2006.

No limitations.

Flying Experience: Total all types 180 hours

Total on type 34 hours

1.6 Aircraft Information

1.6.1 Airworthiness and Maintenance of Aircraft

Manufacturer: Robinson Helicopter Company

Type: R44 Clipper I

Aircraft serial number: 920

Year of manufacture: 2000

Certificate of Registration: Issued on 28 November 2000 in the

ownership of Topjet Aviation Limited

4
 Certificate of Airworthiness: Issued on 15 December 2000 in the

Private Category and valid until 15

December 2005

Engine: Lycoming O-540-F1B5 piston engine

Maximum Approved Gross Weight: 2,400 lb

Total airframe hours: 1,087 hours

1.6.1.1 The helicopter was imported as a new aircraft to Hong Kong in

2000 and had since been registered under Topjet Aviation Limited.

Aircraft technical records indicated that the helicopter had been

maintained in accordance with Maintenance Schedule MS/R44/01

Issue 1 and there had not been any significant airworthiness

problems. The most recent scheduled maintenance check was a

100-hour Inspection carried out on 26 March 2005. At the time

of that inspection, the airframe and engine had each accumulated

1,042 flight hours since new.

1.6.1.2 A review of the Aircraft Log Book indicated that the helicopter

had no outstanding defects prior to the accident flight. The

helicopter was fully serviceable in all respects.

5
1.6.2 Aircraft Description

1.6.2.1 General

R44 is a single-engined helicopter manufactured in the United

States. The maximum gross weight for this helicopter is

2,400 lb. The airframe is primarily constructed of welded steel

tubing covered with aluminium skin and is supported by a skid

type landing gear. The tailcone is a typical monocoque

aluminium structure. There are two front and two rear seats in

the cabin. The helicopter is equipped with dual controls and

certified for single pilot operations on the right front seat. Flight

controls for the left front seat should be removed if the person

occupying this seat is not a rated helicopter pilot.

1.6.2.2 Powerplant and Transmission System

R44 Clipper I is powered by a Lycoming O-540-F1B5 piston

engine with a maximum take-off power rating of 225 shaft horse

power with fuel supply controlled by a carburettor. A pulley

sheave (lower sheave) carried on the horizontal engine output

shaft drives four vee-belts which transmit power to an upper

sheave when the belts are tensioned by an electric screwjack

clutch actuator. When activated, the actuator raises the upper

sheave and automatically sets and maintains the required tension.

An over-running clutch within the upper sheave transmits power

6
 forward to a main rotor gearbox and aft to a tail rotor drive shaft

and also allows the rotors to continue to turn in the event of an

engine stoppage. The main rotor gearbox contains a spiral-bevel

gear set that drives a vertical main rotor shaft. Appendix A

shows a simplified schematic diagram of the powerplant and

transmission system of the helicopter.

1.6.2.3 Main and Tail Rotors

1.6.2.3.1 The main rotor system has two all-metal blades with

stainless steel skin attached to a main rotor hub. The

main rotor hub is mounted to the shaft with a horizontal

teeter hinge located above the coning hinges. The

main rotor rotation is anti-clockwise when viewed from

above. Pitch-change bearings for the blades are

enclosed in a housing at the respective blade root.

1.6.2.3.2 The tail rotor system has two all-metal blades with

aluminium skin. The tail rotor drive shaft, running

inside the tail boom, transmits power to a

splash-lubricated gearbox which in turn drives a

horizontal tail rotor shaft. The two tail rotor blades are

attached to a teetering hub with a fixed coning angle,

elastomeric teetering and Teflon pitch-change bearings.

7
 1.6.2.4 Flight Controls

1.6.2.4.1 R44 has dual controls actuated through push-pull tubes

and bellcranks. The cyclic grip is free to move

vertically and hinges at the centre pivot of the cyclic

stick. The collective stick is equipped with a

twist-grip throttle control. The main rotor blade pitch

angle is controlled by the cyclic stick and the collective

stick.

1.6.2.4.2 The cyclic and the collective control systems are

assisted by three hydraulic servos connecting to the

three push-pull tubes that support the main rotor

swashplate. The hydraulic pump is powered by the

main gearbox so that hydraulic pressure is maintained

as long as the main rotor is rotating.

1.6.2.4.3 Directional control is effected by varying the collective

pitch of the tail rotor blades using yaw pedals which are

connected to the tail rotor blades by push-pull tubes and

bellcranks.

1.6.2.5 Engine Controls

1.6.2.5.1 The engine power is controlled by a twist-grip throttle

located on either of the two interconnected collective

8
 sticks. The throttle actuates the butterfly valve on the

carburettor through a system of push-pull tubes and

bellcranks. When the engine revolutions per minute

(RPM) is above 80%, the electronic governor will be

activated to maintain a constant rotor RPM for various

flight control inputs and helicopter manoeuvres.

While the governor drives the whole throttle system,

including the twist-grip, the pilot may override the

governor with the twist-grip through a friction clutch in

the linkage between the governor and the whole throttle

system.

1.6.2.5.2 The governor system consists of two major components,

namely the governor controller and the governor

assembly. The governor controller is a solid-state

analogue-circuit control unit which senses engine RPM

via tachometer points in the engine right magneto and

provides a corrective signal to the governor assembly.

When activated by the governor controller, the governor

motor drives a friction clutch connected to the throttle to

maintain a constant rotor RPM.

1.6.2.5.3 The R44 Pilot’s Operating Handbook (POH) specifies

that flight with the governor selected ‘OFF’ is

prohibited, except in the case of in-flight malfunction of

the system or for emergency procedures training.

9
1.6.3 Performance and Centre of Gravity

The helicopter was within both longitudinal and lateral centre of gravity

limits. The Maximum Approved Gross Weight of the helicopter is 2,400

lb; the take-off weight of the helicopter was calculated to be approximately

2,200 lb at the time of the accident.

1.6.4 Fuel

The fuel on board was sufficient for the flight.

1.7 Meteorological Information

1.7.1 Weather Forecast and Observations

1.7.1.1 Weather Information issued by the Hong Kong Observatory

1.7.1.1.1 The Hong Kong Observatory (HKO) issues Aerodrome

Routine Meteorological Report (METAR) at half-hour

intervals and Local Aviation Forecasts for 100 nautical

miles radius around Hong Kong at six-hour intervals.

The METARs and Local Aviation Forecasts available to

the pilot during his self-briefing in the morning (see

Paragraph 1.7.3.1) included, amongst others, the

METARs issued between 0000 hrs (0800 hrs) and 0200

hrs (1000 hrs), and the Local Aviation Forecast at 2230

10
hrs (0630 hrs) on the HKO website. The relevant

information is as follows:

(i) METARs at the Hong Kong International

Airport issued between 0000 hrs (0800 hrs)

and 0200 hrs (1000 hrs):

0000 hrs (0800 hrs):

“VHHH 0000 24007KT 220V280 9999

FEW016 30/25 Q1002 NOSIG=”

0030 hrs (0830 hrs):

“VHHH 0030 24009KT 210V280 9999

FEW016 SCT300 30/25 Q1002 NOSIG=”

0100 hrs (0900 hrs):

“VHHH 0100 26009KT 9999 FEW016

SCT300 31/25 Q1002 NOSIG=”

0130 hrs (0930 hrs):

“VHHH 0130 26008KT 9999 FEW020

SCT090 31/25 Q1002 NOSIG=”

0200 hrs (1000 hrs):

“VHHH 0200 25008KT 9999 FEW022

SCT080 31/24 Q1002 NOSIG=”

11
 (ii) Extracts of the Local Aviation Forecast issued

at 2230 hrs (0630 hrs) for the period from

0000 hrs (0800 hrs) to 1000 hrs (1800 hrs):

Surface wind: 220º 10 knots, TEMPO VRB

25 knots, gust 35 knots in thunderstorm.

Offshore wind: 250º 15 knots

Temperature: Offshore 28º C - 33º C

Weather: Hot with sunny periods and isolated

showers. There will also be a few isolated

squally thunderstorms later

Cloud (AMSL): FEW 2000 feet, SCT 4000

feet, TEMPO FEW 1000 feet, SCT CB 1500

feet, BKN 5000 feet

Visibility: 10 KM, TEMPO 3000 M in

showers, TEMPO 1500 M in thunderstorm

Further Outlook: Moderate southwesterly

winds. Mainly cloudy with isolated showers

1.7.1.1.2 The HKO also issued a Local Aviation Forecast at 0430

hrs (1230 hrs) as follows:

Extracts of the Local Aviation Forecast issued at 0430

hrs (1230 hrs) for the period from 0600 hrs (1400 hrs)

to 1600 hrs (2400 hrs):

12
 Surface wind: 220º 10 knots, TEMPO VRB 25 knots,

gust 35 knots in thunderstorm. Offshore wind: 250º 15

knots

Temperature: Offshore 34º C - 28º C

Weather: Mainly fine. There will also be a few isolated

showers and squally thunderstorms inland

Cloud (AMSL): FEW 2000 feet, SCT 8000 feet,

TEMPO FEW 1000 feet, SCT CB 1500 feet, BKN 5000

feet

Visibility: 10 KM, TEMPO 3000 M in showers,

TEMPO 1500 M in thunderstorm

Further Outlook: Moderate southwesterly winds.

Mainly cloudy with isolated showers

1.7.1.2 After the accident, the HKO submitted the following information

on the general weather conditions in Sai Kung area around the

time of the accident:

“Hong Kong was under the influence of southwest monsoon.

Around the time of the incident, winds were southwesterlies and

around 5 – 10 knots in the Sai Kung area and 10 – 15 knots over

Waglan. The weather was generally fine and the visibility

good.”

13
 1.7.1.3 As regards the weather conditions at Pak A, the HKO submitted

the following information:

“Winds and temperatures over the eastern coast (near Pak A) at

0620 UTC were southwesterly 5 – 10 knots and 32 – 33 degree.”

“Winds over Hong Kong picked up slightly around 1400 HKT.

As Pak A was surrounded by hills to its east and west, winds at

Pak A is likely to be affected by its local topography and could be

somewhat different from its surrounding area, especially under

light to moderate wind conditions.”

1.7.2 Meteorological Information Available at the HKAC

The HKAC is a subscriber of the Aviation Meteorological Information

Dissemination System of the HKO. This system displays, inter alia,

METAR, Local Routine Report, Local Aviation Forecast and Winds around

Hong Kong to facilitate the provision, dissemination and display of

meteorological information to users. In addition, the HKAC has access to

the HKO internet website which provides information on aviation weather

observation and forecast.

1.7.3 Meteorological Information Obtained by the Pilot

1.7.3.1 The pilot mentioned in his statement that he had carried out a

self-briefing in the morning prior to the series of flights by

14
 checking the HKO internet website for weather information that

consisted of the actual and forecast weather for aviators, sunrise

and sunset, high and low tide times.

1.7.3.2 From the self-briefing, the pilot gathered that the weather

conditions in general were fine with light and variable winds,

mainly southwesterly; and temperature was 30°C with good

visibility.

1.7.4 Pilot’s Assessment of Wind Conditions at Pak A

1.7.4.1 The pilot stated in his statement that when he made the approach

to Pak A for the landing in the morning, the wind was light,

between 220° and 240° at 5 to 10 knots, and that he was mindful

of tailwind on approach to landing.

1.7.4.2 He also described that the wind was from the southwest just

before the accident.

1.8 Aids to Navigation

The flight was conducted in day time under VFR and the helicopter was

appropriately equipped with navigation aids for such a flight.

15
1.9 Communications

1.9.1 The accident took place at Pak A within Port Shelter, which is one of the

seven Uncontrolled Airspace Reporting Areas (UCARA) in Hong Kong (see

Appendix B). In UCARA, ‘Hong Kong Information’ is the Hong Kong

Air Traffic Service (ATS) unit that provides flight information service (FIS)

and alerting service to aircraft.Note 1 In accordance with the provisions of

the Hong Kong Aeronautical Information Publication issued by the Civil

Aviation Department Hong Kong (CAD), local flights are permitted to take

place under VFR in UCARA, but with an additional requirement for

two-way radio communication with ‘Hong Kong Information’ on the

designated VHF frequency 122.4 MHz.

1.9.2 The helicopter was fitted with a VHF radio communication equipment and

the radio was serviceable on the day of the accident. The helicopter had

been maintaining satisfactory communication with ‘Hong Kong

Information’ within UCARA. The last communication with ‘Hong Kong

Information’ made by the helicopter was at 0610 hrs (1410 hrs) when the

pilot reported lifting off at Pak A shortly before the accident. This

transmission was acknowledged by ‘Hong Kong Information’.

Note 1: FIS refers to a service provided for the purpose of giving advice and information useful for
the safe and efficient conduct of flights. Alerting service refers to a service provided to
notify appropriate organizations regarding aircraft in need of search and rescue aid, and
assist such organizations as required.

16
1.10 Aerodrome Information

The accident took place at an open area at Pak A within UCARA Port

Shelter. Aerodrome information is not relevant.

1.11 Flight Recorders

The helicopter was not fitted with any flight recorder and there was no

requirement for this class of helicopter to be so fitted.

1.12 Wreckage and Impact Information

1.12.1 The impact point was approximately 10 m to the northeast of the lift-off

position (see Photograph 1). The wreckage rested on a slightly sloping

sandy-grassed surface with the fuselage toppled to the left.

1.12.2 The engine remained attached to the airframe but was slightly deformed as a

result of the impact with the ground. The fuel tanks were intact.

1.12.3 Damage to the helicopter as a result of the impact was as follows (see

Photograph 2). Additional photographs showing the damage to the

helicopter are included in Appendix C.

(a) The left skid was substantially damaged.

(b) The main rotor blades remained attached to the helicopter but were

significantly bent and twisted.

17
 (c) Both blades of the tail rotor were severed. One of the two tail rotor

blades was subsequently recovered at approximately 2 m from the tail

rotor hub whereas the other piece could not be located despite extensive

search of the accident site.

(d) The tail boom was severely fractured, locally twisted and bent to the

starboard near the tail rotor drive shaft damper bearing.

(e) The perspex canopy was extensively damaged.

Photograph 2 Helicopter Wreckage

1.12.4 The left yaw pedal was found at the full forward position in the

post-accident examination.

18
1.12.5 The flight controls for the left front seat were found undamaged, adjacent to

the storage compartment underneath the left front seat normally used for

stowing the flight controls.

1.13 Medical and Pathological Information

1.13.1 The Pilot

1.13.1.1 The pilot was in possession of a valid Class 2 Medical Certificate

and he operated the helicopter from the right front seat. There

was no evidence to suggest that he was suffering from any

pre-existing illness that might have contributed to the accident.

According to the pilot’s statement, he was not taking any

medicines prescribed by a doctor or purchased over the counter.

1.13.1.2 The pilot was diagnosed with compression (burst) fracture of the

first lumbar spinal vertebra. There were no other significant

injuries. The spine injury was wholly compatible with the

mechanism of trauma caused by the helicopter’s vertical

deceleration forces in the accident.

1.13.1.3 Blood and urine tests for drugs and alcohol using automated

liquid chromatography were conducted after the accident.

1.13.1.4 There was no evidence to suggest that the performance of the pilot

had been affected by tiredness, alcohol, drugs, physiological

19
 factors or incapacitation.

1.13.2 Left Front Seat Passenger

This passenger sustained a compression fracture of the first lumbar spinal

vertebra.

1.13.3 Left Rear Seat Passenger

1.13.3.1 The passenger, a R44 type rated helicopter pilot herself, had

assisted the pilot in escorting the other passengers into and out of

the helicopter during flights. She sustained a compression

fracture of the second lumbar spinal vertebra.

1.13.3.2 She was not entrapped in the wreckage but she decided to remain

inside the helicopter until she was attended to by the emergency

service personnel. She was subsequently evacuated from the

helicopter after part of the roof of the helicopter was cut away by

the Fire Services Department (FSD) personnel.

1.13.4 Right Rear Seat Passenger

This passenger was not injured in the accident and was not admitted to

hospital. At the time of helicopter impact with the ground, he was

momentarily leaning forward off his seat in an attempt to comfort the left

front seat passenger. He was not entrapped in the accident and managed to

20
 vacate the wreckage without assistance.

1.14 Fire

No fire occurred in the accident.

1.15 Survival Aspects

1.15.1 Search and Rescue (SAR)

The accident took place at 0612 hrs (1412 hrs), and about 5 minutes later a

member of the public telephoned to report the occurrence to the Kowloon

Regional Command & Control Centre (RCCC/K) of the Hong Kong Police

(HKP), who then informed the Marine RCCC (RCCC/M) of the HKP and

the Fire Services Communication Centre (FSCC) of the FSD to take

corresponding actions. Emergency service personnel of the HKP, FSD and

Government Flying Service (GFS) were subsequently notified and

dispatched in the rescue operation. A summary of the emergency handling

of the rescue operation is contained in Appendix D.

1.15.2 Aircraft Survivability

Crashworthiness survivability analyses were conducted which included an

assessment of the container, restraints, environment, energy absorption

features and post-crash factors.

21
1.16 Tests and Research

1.16.1 Components affecting engine controls and flying controls were inspected.

For those components that required the use of specialist instruments and

equipment to verify the integrity and functionality, they were further tested

in the laboratory by the aircraft manufacturer in the United States and an

independent metallurgical laboratory in Hong Kong.

1.16.2 Four components, namely the hydraulic pump, the right magneto, the

governor controller and the governor motor were sent to the aircraft

manufacturer for detailed examination under the supervision of the United

States National Transportation Safety Board (NTSB).

1.16.3 An independent metallurgical laboratory conducted an analysis of the tail

rotor drive shaft, the tail rotor hub and the blades of the tail rotor of the

helicopter. Stereomicroscopic examinations were carried out on the drive

shaft, rotor hub and broken tail rotor blades to ascertain whether there was

any pre-impact damage and to establish the cause of the breakage.

1.17 Organization and Management Information

The helicopter was registered in Hong Kong under the ownership of Topjet

Aviation Limited with a Certificate of Airworthiness in the Private Category.

Aircraft maintenance services and hangarage of the helicopter were

provided by the HKAC.

22
2. ANALYSIS

2.1 Flight Operations and Aircraft Airworthiness

2.1.1 Vibration and Noise

The pilot did not report noticing any abnormal vibration, unusual noise,

illumination of warning lights or sounding of warning horn from the

moment of lift-off until the impact. Furthermore, according to the

statement of the left front seat passenger, she did not notice anything

abnormal in the cockpit such as flashing lights on the instrument panel or

warning sounds after lift-off. This indicated that the helicopter did not

experience any system failure or malfunction from the moment of lift-off

until the steady hover.

2.1.2 Flying Controls

2.1.2.1 Cockpit Switches

All cockpit switches were found in their normal positions for

flying except the following:

2.1.2.1.1 The master battery switch was in the ‘OFF’ position.

When interviewed after the accident, the pilot

confirmed that he had placed the master battery switch

23
 to the ‘OFF’ position after the impact.

2.1.2.1.2 The governor switch, located at the end of collective

control, was found at the ‘OFF’ position (see

Photograph 3).

Left front seat Right front seat

Governor at
‘OFF’ Position

Photograph 3 Governor Switch at ‘OFF’ Position

When interviewed after the accident, the pilot stated that

he had been trained to memorize the preflight checklist

and that as per his usual practice, he had performed the

24
 preflight checks by reciting the checklist on each

take-off. The Preflight Checks as stated in the R44

POH require the governor to be selected ‘ON’ and

verified operative before flight. As stated in Paragraph

2.1.1, the pilot did not report noticing illumination of

‘GOV OFF’ (indicating governor disabled). The pilot

also confirmed in his statement that the helicopter had

entered into a steady hover, and this was supported by

the left rear seat passenger in her statement. The

warning light bulb of the governor was tested after the

accident and was found to be serviceable. The right

magneto, governor controller and governor motor were

returned to the aircraft manufacturer for functional

testing and these components were found to be

operating normally. All the above indicated that the

governor was selected ‘ON’ from the moment of lift-off

until the steady hover. It was reasonably believed that

the governor switch was inadvertently knocked into the

‘OFF’ position after the accident, most probably during

the evacuation of the occupants from the helicopter.

2.1.2.2 Flight Controls

As mentioned in Paragraph 1.12.5, the flight controls for the left

front seat were found undamaged, adjacent to the storage

compartment underneath the left front seat normally used for

25
 stowing the flight controls. This indicated that the flight controls

for the left front seat were removed prior to the accident flight for

single pilot operations on the right front seat (see Paragraph

1.6.2.1).

2.1.3 Tail Rotor Blades

2.1.3.1 The tail rotor blades were severed by impact with the ground.

Both ends were fractured at approximately the same distance from

the centre of the tail rotor hub assembly (see Photograph 4) and

found to have sustained similar breakage, indicating that the tail

rotor was still running when it hit the ground. Judging from the

breakage of tail rotor blades, the damage to both blades was likely

to be symmetrical, i.e. each of the two blades was severed into

two pieces.

27 cm 30 cm

Normal Blade Length (measured from the centre of tail rotor hub) 69 cm

Photograph 4 Tail Rotor Hub and Broken Blade

2.1.3.2 Comprehensive search over an extensive area of approximately

160 m in diameter as shown in Photograph 5 was conducted in an

attempt to recover the missing part of the broken tail rotor blade

26
 but it could not be located.

160 m

Photograph 5 Search Area for Missing Part of Broken Tail Rotor Blade

2.1.3.3 An independent metallurgical laboratory conducted an analysis of

the tail rotor hub and the blade of the tail rotor of the helicopter.

The results indicated that the tail rotor hub and the tail rotor

blades did not have any pre-impact damage. In addition, the

fracture surfaces of the blades did not indicate any signs of metal

fatigue. The fracture of blades was most probably caused by a

combination of tearing, bending and twisting forces acting on the

rotating blades when they struck the ground. Had the breakage

27
 of the tail rotor blades occurred during the hover manoeuvre, the

pilot would have experienced extreme vibration. Since none of

the occupants reported noticing any extreme vibration or

significant noise during the hover manoeuvre, it could be

concluded that the tail rotor did not suffer from any damage until

it hit the ground.

2.1.4 Tail Rotor Drive Shaft

The laboratory examination on the breakage of the broken ends of the tail

rotor drive shaft suggested that the engine was still providing power to the

tail rotor system before the impact and that the power was sufficient to have

twisted the drive shaft to failure as the tail rotor was abruptly stopped from

rotating upon hitting the ground (see Photographs 6a and 6b).

Photograph 6a Photograph 6b
Broken End of Tail Rotor Drive Shaft The Other Broken End of Tail Rotor Drive Shaft

2.1.5 Tail Rotor Control System

Post-accident examination of the tail rotor control system revealed that the

28
 yaw pedals, the associated linkages and the rotor hub of the system were

functional.

2.1.6 Contact with Foreign Objects

It was believed that whilst the helicopter was in the hover, had the rotating

tail rotor struck or been deformed by any foreign object such as a plastic

bag, some marks would have been left on the surface of the tail rotor and

unusual noise and vibration would have been generated and noticed by the

occupants. A laboratory examination of the broken tail rotor system did

not reveal any foreign object damage and there was no trace of plastic bags

on the remaining rotor blade. Furthermore, none of the occupants reported

noticing any unusual noise or significant vibration from the moment of

lift-off until the impact. It could therefore be concluded that the tail rotor

had not come into physical contact with any foreign object in flight.

2.1.7 Hydraulic Pump, Right Magneto, Governor Controller and Governor Motor

The hydraulic pump, the right magneto, the governor controller and the

governor motor were subjected to detailed examination by the aircraft

manufacturer under the supervision of NTSB. The examination results

indicated that these components functioned properly.

2.1.8 Surface Wind Conditions and Topographic Effects at Pak A

2.1.8.1 As mentioned in Paragraph 1.7.1.3, the HKO submitted that

29
winds at Pak A were likely to be affected by its local topography

and could be somewhat different from its surrounding area,

especially under light to moderate wind conditions. As shown in

Map 1 and Photograph 7, the accident site was situated along the

coast of Pak A with hills to the east and the west, and a narrow

valley running to the north towards the High Island Reservoir.

With the prevailing southwesterly wind conditions of 5 to 10

knots from the sea as reported by the pilot, it was likely that the

accident site could be subjected to ‘valley effect’, such that pilots

would usually expect an increase in the strength of the surface

winds as the winds were funneled towards the narrow valley.

Pak A

Map 1 Geographical Location of Pak A

30
 N

Valley towards
the High Island
Reservoir

Wreckage

Photograph 7 Topography at Pak A

2.1.8.2 In the pilot’s assessment (see Paragraph 1.7.4), he stated that the

wind was coming from between 220° and 240° at 5 to 10 knots

earlier of the day. He further stated that he initiated a slow 180°

spot turn to the right, manoeuvring the helicopter to a southerly

direction into wind. It was therefore evident that the helicopter

had lifted off in a tailwind condition.

31
 2.1.8.3 As regards the wind strength, the pilot stated that the wind was 5

to 10 knots in the morning. According to the reports from HKO

(see Paragraph 1.7.1.3), the wind over Hong Kong had in general

picked up speed in the afternoon. Combining this change with

the influence of ‘valley effect’, a wind stronger than that

anticipated by the pilot might have prevailed over Pak A at the

time of the accident flight. However, in the absence of a

real-time measurement of on-scene wind data, the exact surface

wind conditions over Pak A at the time of the accident could not

be accurately determined.

2.1.9 Aerodynamic Effects on Tail Rotor

The following is a discussion of the basic helicopter aerodynamic principles

(see Paragraphs 2.1.9.1 – 2.1.9.4) and a detailed analysis of the aerodynamic

effects (see Paragraphs 2.1.9.5 – 2.1.9.13) on the tail rotor of the accident

flight from the initial tailwind hover to the loss of directional control of the

helicopter in the yawing plane based on the following findings:Note 2

(a) the description of the flight by the pilot and left rear seat passenger;

(b) the wind, according to the pilot’s assessment, was from a southwesterly

direction;

Note 2: The diagrams within this analysis are for illustration purpose and may be out of scale. For
simplicity and clarity, some of the forces acting on the aerofoil of a rotor disc are omitted in
all the diagrams and the forces shown do not act from the centre of pressure.

32
(c) the strength of the wind, according to the information from HKO, was at

5 to 10 knots near Pak A at 0620 hrs (1420 hrs);

(d) the tail rotor drive shaft and the tail rotor were fully functional before

the impact;

(e) the effectiveness of the tail rotor had not been affected by any foreign

object; and

(f) the engine was providing sufficient power to the main rotor for the

hover.

2.1.9.1 Helicopter Stability when Hovering Tailwind

2.1.9.1.1 As the helicopter was hovering tailwind, the wind

would become turbulent after the airflow was affected

by the tail rotor and the helicopter fuselage before

meeting the main rotor disc. As a result, it would be

more difficult to control the helicopter as compared

with hovering into wind.

2.1.9.1.2 Furthermore, the helicopter by design resembles a

weathervane and is subjected to weathercock effect

which attempts to weathervane the nose of the

helicopter into the relative wind. Once the helicopter

starts to turn into the wind from the tailwind position,

the rate of turn will accelerate accordingly.

33
2.1.9.2 Anti-Torque Effect and Tail Rotor Thrust

Figure 1 is an illustration of the Anti-Torque Effect of the

helicopter in the hover. With the main rotor blades rotating

anti-clockwise, the helicopter would have a tendency to turn

clockwise. This phenomenon is known as the Anti-Torque

Effect, which can be seen as Force Z1 and Z2 (of equal magnitude)

acting on the fuselage and forcing the helicopter to yaw to the

right. To prevent the helicopter from yawing to the right, the tail

rotor of the helicopter would produce a Tail Rotor Thrust (i.e.

Force X1 and X2) to counter the effect of Z1 and Z2.

Z1 Anti-clockwise Rotation
of Main Rotor Blades
Tail Rotor Blades

Z2 X1 X2

Anti-Torque Effect Tail Rotor Thrust

Figure 1 Anti-Torque Effect and Tail Rotor Thrust

34
2.1.9.3 Induced Flow and Rate of Turn Flow

2.1.9.3.1 Induced Flow

As a result of the Tail Rotor Thrust, an Induced Flow of

air mass in the opposite direction would be produced as

shown in Figure 2.

Direction of Induced Flow Direction of Tail Rotor Thrust

Figure 2 Induced Flow and Tail Rotor Thrust

2.1.9.3.2 Rate of Turn Flow

As the helicopter turns right in the yawing plane, an air

flow acting on the tail rotor blade in the opposite

direction of the Induced Flow as shown in Figure 3 will

be produced. This air flow is referred to as the Rate of

Turn Flow in the following analysis. The magnitude

35
 of the Rate of Turn Flow will vary with the rate of turn

of the helicopter.

Helicopter Yaw Turn

Direction of Induced Flow Direction of Rate of Turn Flow

Figure 3 Induced Flow and Rate of Turn Flow during the Yaw Turn

2.1.9.4 Induced Flow and Tail Rotor Thrust

The Induced Flow (IF) had a major effect on the aerodynamics of

a helicopter. The Relative Air Flow (RAF) is the resultant of the

Induced Flow, Rate of Turn Flow and Rotational Air Flow along

the Plane of Rotation (POR) of the rotor blades. In the following

analysis, the Net Induced Flow will be resulted when the Induced

Flow is greater than Rate of Turn Flow. An increase of the Net

Induced Flow would result in a decrease in the Angle of Attack

α (i.e. the angle between the RAF and the chord of the rotor

blades), which would in turn result in a decrease in the Lift.

Consequently, the Tail Rotor Thrust would be reduced as shown in

Figure 4.

36
 Aerofoil section LIFT
REDUCED α

REDUCED LIFT
RAF
RAF
Net IF
α Increased Net IF

Rotational Air Flow Rotational Air Flow

POR POR

Figure 4 Aerodynamic Relationship between Induced Flow and Lift

2.1.9.5 Analysis of the Accident Flight – From Lifting-off to a Hover

2.1.9.5.1 With a high all up weight of approximately 2,200 lb

(see Paragraph 1.6.3) and in a tailwind condition, the

tail rotor of the helicopter had to produce more Tail

Rotor Thrust. This would require a high Pitch Angle

β (i.e. the angle between the tail rotor blades and the

POR) of the tail rotor blades, resulting in a high Angle

of Attack α, as shown in Figure 5.

N LIFT

RAF
Net IF
Rotational Air Flow
POR
β

Figure 5 Hovering Tailwind with a High All Up Weight

37
 2.1.9.5.2 As discussed in Paragraph 2.1.8, it was possible that the

wind velocity at the time of the accident was greater

than the wind reported in the surrounding area by the

HKO due to ‘valley effect’ as the winds were funneled

towards the narrow valley. As the helicopter lifted off

tailwind with a crosswind component from the left, it

would be subjected to a weathercock effect trying to

turn the helicopter to the left in the yawing plane as

described in Paragraph 2.1.9.1.2. In order to maintain

the directional control to achieve a steady hover, it was

believed that the pilot must have applied some right yaw

pedal to counter the weathercock effect.

2.1.9.6 Initiation of the 180° Turn to the Right

2.1.9.6.1 Having established into a tailwind hover with a

component of wind from the left, the pilot initiated a

slow 180° spot turn to the right, as stated in his

statement: “… I then came up to a five-foot steady

hover facing north. I did the hover checks including

the RPM. I initiated a slow 180° spot turn to the

right. …”. To do this, he would have to further apply

additional right yaw pedal, which would result in a

reduction of the Pitch Angle and the Angle of Attack in

the tail rotor. As the helicopter started to turn to the

38
 right, the relative wind gradually changed to a direct

tailwind position as shown in Figure 6. At this time,

the weathercock effect trying to turn the helicopter to

the left in the yawing plane would disappear. Under

the circumstances, the pilot would need to apply some

left yaw pedal to compensate the right yaw pedal

originally applied as discussed in Paragraph 2.1.9.5.2, in

order to control the rate of turn of the helicopter.

N
LIFT
Reduced α during Yaw Turn

RAF
Net IF

Rotational Air Flow

POR
Reduced β during Yaw Turn

Figure 6 Application of Right Yaw Pedal to Turn Right

2.1.9.6.2 As the helicopter continued to turn right, the relative

wind would now change from a tailwind position to a

crosswind position with a crosswind component acting

on the tail rotor from the right. This crosswind

component would act in the same direction of the

Induced Flow, thus increasing the magnitude of the

Induced Flow. This would result in a further decrease

of the Angle of Attack, and thus the Tail Rotor Thrust.

39
 2.1.9.7 Loss of Tail Rotor Effectiveness

With the decrease in Tail Rotor Thrust, the rate of yaw to the right

would increase even without any application of right yaw pedal.

At the same time, the helicopter would be affected by the

weathercock effect as mentioned in Paragraph 2.1.9.1.2, resulting

in further acceleration in the rate of turn. The combined effect of

the additional Induced Flow and weathercock effect would be at

its maximum when the wind was from the 3 o’clock position as

shown in Figure 7. The rate of turn of the helicopter would then

continue to increase until the helicopter turned into wind. This

phenomenon of the uncommanded increase and accelerating rate

of turn is commonly known as Loss of Tail Rotor Effectiveness

(LTE).Note 3 Had the limitation of the maximum rate of turn of

the helicopter been available to the pilot in the R44 POH, the pilot

would have been better alerted to the development of LTE and

possibly the subsequent Loss of Tail Rotor Thrust (LTT) arising

from an uncommanded, rapid and accelerating rate of turn.

Note 3: CAD issued a letter in January 2004 to the HKAC and the other helicopter operators in Hong
Kong to promulgate a Flight Operations Department Communication 1/2004 produced by the
United Kingdom Civil Aviation Authority (UKCAA) on the subject of ‘Loss of Tail Rotor
Effectiveness’ (see Appendix E).

40
 N

REDUCED LIFT
RAF
Additional IF due to wind α
Net IF

Rotational Air Flow

POR

Figure 7 Wind from 3 o’clock Position

2.1.9.8 Action Required under LTE

As soon as the helicopter entered into the initial state of LTE, it

would be important for the pilot to arrest the increasing rate of

turn by the timely application of left yaw pedal. As mentioned

in Paragraph 2.1.9.1, hovering tailwind would make it more

difficult to control the helicopter and involve a relatively higher

level of pilot workload. While the pilot intended to make a slow

spot turn as mentioned in Paragraph 2.1.9.6, the left rear seat

passenger noted a rapidly increasing rate of turn as described in

the following recollection: “… It was an abrupt spot turn to the

right. It started quickly and kept accelerating. …”. There was

no evidence to indicate that the pilot had taken effective action to

control the unanticipated increasing rate of turn during the initial

180° spot turn.

41
2.1.9.9 Helicopter Turning into the Wind

2.1.9.9.1 Whilst the helicopter was in a turn, the tail rotor would

be subjected to vortex ring effect due to the meeting of

the Induced Flow and the Rate of Turn Flow causing

vortices to form on the periphery of the tail rotor disc,

spreading inboard as a result of the increasing Rate of

Turn Flow. The vortices would disturb the air flow

around the tail rotor, leading to the loss of Tail Rotor

Thrust. Furthermore, as the helicopter was turning

into the wind, the tail rotor would also be affected by

the vortices created by the main rotor downwash. This

would result in the further loss of Tail Rotor Thrust

available to the tail rotor, aggravating the uncontrolled

yaw turn situation and further accelerating the turn.

2.1.9.9.2 As the helicopter continued to yaw to the right, the wind

direction relative to the helicopter changed from 3

o’clock position to 12 o’clock position. The additional

Induced Flow due to wind would decrease to zero when

the helicopter was into wind. In the meantime, the

increasing rate of turn generated a progressively

stronger Rate of Turn Flow. Consequently, the Rate of

Turn Flow might be larger than the Induced Flow so

that there would be a Net Rate of Turn Flow acting on

the other side of the POR as shown in Figure 8. As

42
 shown in the same figure, the RAF might then act on

the other side of the POR. As a result, the Angle of

Attack α would significantly increase, approaching

the Critical Angle of Attack (Stalling Angle of Attack).

Rotational Air Flow

α
Net Rate of Turn Flow
RAF POR

Figure 8 Helicopter Facing the Wind

2.1.9.10 Tail Rotor Stall

The pilot stated in his statement that when the helicopter was into

wind, he applied left yaw pedal to stop the turn: “… I applied left

pedal, intending to stabilize the helicopter in a hover facing south

before transitioning forward. However, the helicopter seemed

not to respond to my pedal input. The helicopter did not stop

turning on a southerly heading. The rate of turn was building up,

getting faster and faster. …”. It was believed that the pilot

under the circumstances had applied a substantial amount of left

yaw pedal in an attempt to arrest the high rate of turn. This

explained the finding that the left yaw pedal was found in the full

43
 forward position in the post-accident examination. This

application of the left yaw pedal at this stage however could have

inadvertently caused the Angle of Attack α to exceed the

Critical Angle of Attack as shown in Figure 9. As a result, the

tail rotor entered into a state of incipient stall, and had eventually

stalled, resulting in a LTT situation.

No Lift at Stalling Angle of Attackα

Stall Occurred

α
Rotational Air Flow

Net Rate of Turn Flow

POR
RAF

Figure 9 Tail Rotor Stall

2.1.9.11 Procedures for Loss of Tail Rotor Thrust

It was highly likely that at this time, the pilot devoted full

attention to regain directional control of the helicopter, became

disoriented in the uncontrolled right turns and did not realize that

the helicopter might have experienced a LTT. As a result, he did

not carry out the procedures as specified in the section ‘LOSS OF

TAIL ROTOR THRUST DURING HOVER’ in the R44 POH

44
 Page 3-5 (see Appendix F). Had the pilot realized that the

helicopter had experienced LTT and followed the procedures in

accordance with the R44 POH, the effect of the rapid rate of turn

might not have been exacerbated once the anti-torque effect was

eliminated and the pilot could have been able to cushion the

forced landing by raising the collective.

2.1.9.12 Left Drift of the Helicopter due to Loss of Tail Rotor Thrust

Judging from the toppling of the helicopter wreckage on its left

side and the damage to the left skid, it was believed that whilst the

helicopter was yawing to the right, it had also been drifting to the

left at the impact. Aerodynamically, the horizontal component

of the main rotor thrust would compensate the horizontal

component of tail rotor thrust to prevent the helicopter from

drifting as shown in Figure 10a. The helicopter would therefore

hover with left skid low. However, if there was a loss of tail

rotor thrust, the helicopter would drift to the left after it had

executed the first 180° turn to the right in the yawing plane, due to

the horizontal component of the main rotor thrust as shown in

Figure 10b. From the left drifting of the helicopter, it could be

substantiated that the helicopter had experienced a loss of tail

rotor thrust during the accident.

45
 Tail Rotor Thrust in Action Loss of Tail Rotor Thrust
No drift Drift to the Left

Horizontal Component Horizontal Component

of Main Rotor Thrust of Main Rotor Thrust

Horizontal Component
of Tail Rotor Thrust

Figure 10a Figure 10b

Figure 10 Left Drift of the Helicopter due to Loss of Tail Rotor Thrust
(Viewed from the rear of the helicopter)

2.1.9.13 Although the pilot could not recall the exact number of rounds the

helicopter had turned, he stated in his statement that he had “faced

the sea for the second time” during the process. Based on this

pilot’s account of the accident, it could be deduced that the

helicopter had completed at least two and a half revolutions

before the eventual impact.

2.2 Meteorology

2.2.1 The pilot mentioned in his statement that he had carried out a self-briefing

in the morning prior to the series of flights by checking the HKO website

for weather information that consisted of the actual and forecast weather for

aviators. Due to the fact that Local Aviation Forecasts are issued by the

HKO once every six hours, and judging from the time of the pre-flight
46
 weather self-briefing conducted, it was highly probable that the pilot would

have referred to the Local Aviation Forecast issued at 2230 hrs (0630 hrs)

that covered the period from 0000 hrs (0800 hrs) to 1000 hrs (1800 hrs),

within which the planned flights would take place. The next Local

Aviation Forecast was issued at 0430 hrs (1230 hrs). Both the Local

Aviation Forecasts issued at 2230 hrs (0630 hrs) and 0430 hrs (1230 hrs)

indicated consistent surface wind condition of 220° at 10 knots varying at

25 knots, gusts 35 knots in thunderstorm. However, it should be noted that

the coverage of these Local Aviation Forecasts was for 100 nautical miles

radius around Hong Kong. Furthermore, it was confirmed that there was

no report of thunderstorm for the period in the vicinity of Pak A.

2.2.2 At the time of the accident, the weather at or in the vicinity of Pak A where

the accident occurred was generally fine with good visibility. According

to the pilot’s statement, the wind in the morning was coming between 220°

and 240° at 5 to 10 knots. The left rear seat passenger described that the

helicopter came to a five-foot hover with a light tailwind. From the

information provided by two pilots engaged in the subsequent rescue

operation, and the rescue personnel on scene, as well as post-accident

meteorological review made by the HKO, it could be established that the

general surface wind direction in Pak A area were consistent with the

forecasts at 2230 hrs (0630 hrs) and 0430 hrs (1230 hrs) and the pilot’s

assessment in Paragraph 1.7.4.

2.2.3 The surface winds over Pak A were likely to be affected by the local

topography according to the HKO. As analyzed in Paragraph 2.1.8, the

47
 prevailing winds at the time of the accident might have been stronger than

the 5 to 10 knots as experienced by the pilot in the morning and anticipated

for the flight in the afternoon.

2.3 Communications and Navigation Aids

The flight took place at Pak A within UCARA Port Shelter with satisfactory

two-way radio communication with ATS units. The helicopter was

appropriately equipped with navigation aids for VFR flights. Therefore,

radio communications and navigation aids did not contribute to this

accident.

2.4 Aircraft Survivability

2.4.1 Crashworthiness survivability analyses were conducted which included the

following aspects:

(a) Container – structural airframe crash resistance, cockpit and cabin space

integrity, resistance to incursion by external objects

(b) Restraints – occupant harnesses

(c) Environment – whole body deceleration, limb protection, impact with

cockpit structures

(d) Energy Absorption Features – design of seats and aircraft structure

(e) Post-Crash Factors – exits, entrapment, escape, fire and smoke, search

and rescue organization.

48
2.4.2 Container

Although the general shape and dimensions of the cockpit and occupant

space were preserved, the perspex canopy was extensively damaged

following the impact. Impact damage to the left underside of the fuselage

(see Photograph 8) resulted in approximately 1 cm upward displacement of

the left rear seat. This damage reflects the significant vertical deceleration

forces applied to the occupants, and which caused the spine injuries.

There was no evidence of any other significant injury to the pilot or

passengers attributable to the structural damage or to intruding external

objects.

Original position of the Left rear seat Upward displacement of

base of the fuselage
the base of the fuselage

Sand bags
supporting
the
helicopter
wreckage

Photograph 8 Deformation of the Left Underside of the Fuselage due to the Accident
(Left Side View)

49
2.4.3 Restraints

The three-point inertia-reel harnesses restrained the pilot and passengers.

These harnesses were attached wholly to the helicopter cockpit frame

structure and were fastened by standard flap release buckles mounted on

short straps attached to the frame. According to the pilot’s statement, he

had checked that the passengers were all secured in their seat belts before

the take-off of the accident flight. Statements of the passengers confirmed

that their harnesses were fastened at the time of the impact. The pilot and

passenger seats were constructed integrally with the floor and comprised a

pressed-sheet aluminium frame and seat cushion backed by aluminium plate.

It was concluded that the three-point harnesses functioned normally and did

not contribute to any injury or entrapment of the occupants.

2.4.4 Environment

There was no evidence of any injury caused by protruding objects within

the cabin, nor of any malfunction causing injury. There was no post-crash

fire or smoke, nor any clear evidence of fuel, lubricant or hydraulic fluid

leakage that might have presented a toxic or physical hazard within the

cabin.

2.4.5 Energy Absorption Features

Standards pertaining to this helicopter are based on the United States’

Federal Aviation Regulations (FAR) – FAR 27.561 effective 01/02/1965

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 which requires that occupants have a reasonable chance of escaping when

impact forces applied to them do not exceed those in the following table:

Requirements

Load Directions FAR 27.561 effective 01/02/1965

Upward 1.5 g

Forward 4g

Sideward 2g

Downward 4g

It was not possible to accurately determine the actual crash forces in this

accident from the available evidence.

2.4.6 Post-Crash Factors

2.4.6.1 Escape/Exits

The accident occurred at 0612 hrs (1412 hrs). The pilot and two

passengers escaped from the helicopter, two of them through the

broken canopy and the other through the right side cockpit door.

Escape via the left side door was impossible, as the helicopter was

lying on its left and this door was obstructed by contact with the

ground.

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2.4.6.2 Entrapment

There was no evidence of physical entrapment of the pilot or the

passengers, but the left rear seat passenger decided to remain in

the cabin. After the roof of the helicopter was cut away by the

emergency service personnel, she was released from the wreckage

at approximately 0730 hrs (1530 hrs), i.e. 1 hour 18 minutes after

the accident.

2.4.6.3 Fire and Smoke

There was no post-crash fire.

2.4.6.4 Search and Rescue

At 0617 hrs (1417 hrs), a ‘999’ caller alerted the emergency

services to the location of the accident. The first resource to

arrive on-scene was a GFS AS332 L2 helicopter at approximately

0632 hrs (1432 hrs). The injured pilot and the injured left front

seat passenger were airlifted by GFS helicopter at 0649 hrs (1449

hrs) and 0659 hrs (1459 hrs) respectively. The last injured

person (i.e. the left rear seat passenger who remained in the cabin)

was attended to by a doctor of the GFS and airlifted from the

scene at 0741 hrs (1541 hrs).

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2.4.7 Based on the above analysis, it was concluded that the accident was fully

survivable.

2.5 Air Traffic Service

2.5.1 The helicopter received FIS from ‘Hong Kong Information’ and the

provision of such service was appropriate.

2.5.2 On receipt of a ‘999’ call, FSCC alerted the duty Aerodrome Supervisor of

the accident who then initiated subsequent alerting actions in accordance

with CAD Air Traffic Management Division Emergency Procedures Manual.

The provision of alerting service by ATS units was in order.

2.6 Emergency and Rescue Services

2.6.1 The accident site was remote and not easy to access by road. Rescue

personnel attended to and arrived at the site by air, sea and land as detailed

in Appendix D. The injured persons were then evacuated from the

helicopter, attended to by the medical personnel on-scene and subsequently

airlifted to the hospital in a prompt manner.

2.6.2 The alerting action, emergency response and level of attendance of the

emergency service personnel were efficient and effective.

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3. CONCLUSIONS

3.1 Findings

3.1.1 The pilot held a valid Private Pilot’s Licence (Helicopters) on type with a

valid Class 2 Medical Certificate. (Paragraph 1.5)

3.1.2 There was no evidence to suggest that the performance of the pilot had been

affected by tiredness, alcohol, drugs, physiological factors or incapacitation.

(Paragraph 1.13.1.4)

3.1.3 The pilot conducted a self-briefing on the weather conditions of the Hong

Kong area prior to the series of flights and was aware of tailwind on

approach to landing. (Paragraphs 1.7.3.1 and 1.7.4)

3.1.4 The pilot checked that the passengers were all secured in their seat belts

before the take-off of the accident flight. (Paragraph 2.4.3)

3.1.5 The pilot had operated into and out of Pak A before the accident on the same

day. The accident occurred in the afternoon during departure on the

second run from Pak A with three passengers on board. (Paragraphs 1.1.1

and 1.1.2)

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3.1.6 On departure of the accident flight, the pilot brought the helicopter to a

tailwind hover and then made a right yaw turn with the intention of turning

the helicopter 180° into wind for the take-off. However, the pilot was not

able to arrest the accelerating rapid rate of turn. (Paragraphs 2.1.8,

2.1.9.6 and 2.1.9.7)

3.1.7 The tail rotor stalled after the helicopter had first turned through the

southwesterly wind and the helicopter subsequently entered into

uncontrolled right turns. (Paragraphs 2.1.9.10 and 2.1.9.11)

3.1.8 The helicopter made at least two and a half revolutions before it impacted

on the ground. (Paragraph 2.1.9.13)

3.1.9 Three persons (i.e. the pilot, left front seat passenger and left rear seat

passenger) sustained lumbar spine injuries. The right rear seat passenger

was uninjured. (Paragraphs 1.2 and 1.13)

3.1.10 No occupants were entrapped in the accident. The injured left rear seat

passenger decided to remain inside the helicopter until she was

subsequently evacuated from the helicopter by the emergency service

personnel. (Paragraphs 1.13.3.2 and 2.4.6.2)

3.1.11 The accident was survivable. (Paragraph 2.4.7)

3.1.12 All injured persons were airlifted to hospital by rescue helicopters without

undue delay. (Paragraph 2.6.1)

55
3.1.13 The surface wind direction at Pak A area was southwesterly and its strength

was assessed and anticipated by the pilot as 5 to 10 knots. However, the

prevailing wind strength at the time of accident might have been in excess

of 5 to 10 knots due to the ‘valley effect’. (Paragraphs 1.7.4, 2.1.8 and

2.2.3)

3.1.14 The flight was conducted in day time under VFR and the helicopter was

appropriately equipped with navigation aids for such a flight. (Paragraph

1.8)

3.1.15 Communications between the pilot and the ATS units were satisfactory.

(Paragraph 2.3)

3.1.16 The alerting actions, response and attendance by the ATS units and

emergency service personnel were efficient and effective. (Paragraphs

2.5, 2.6 and Appendix D)

3.1.17 The helicopter had a valid Certificate of Airworthiness and was maintained

in accordance with the approved maintenance schedule. (Paragraph

1.6.1)

3.1.18 The main rotor blades remained attached to the helicopter but were

significantly bent and twisted as a result of impact with the ground.

(Paragraph 1.1.3)

56
3.1.19 The fuel tanks of the helicopter were intact in the accident and there was no

leakage of fuel. (Paragraph 1.12.2)

3.1.20 Both tail rotor blades of the helicopter were severed on impact with the

ground, and one piece of the severed blades could not be found.

(Paragraphs 1.12.3 and 2.1.3)

3.1.21 The tail rotor had not come into physical contact with any foreign object in

flight and it did not suffer from any damage until it hit the ground.

(Paragraphs 2.1.3.3 and 2.1.6)

3.1.22 The tail boom of the helicopter was severely fractured, locally twisted and

bent to the starboard near the tail rotor drive shaft damper bearing.

(Paragraph 1.1.3)

3.1.23 The helicopter had no outstanding defects prior to the accident flight and

was fully serviceable in all respects. (Paragraph 1.6.1.2)

3.1.24 The POH did not specify the maximum rate of turn limitation of the

helicopter. (Paragraph 2.1.9.7)

3.2 Cause

3.2.1 The helicopter experienced, during a yaw turn to the right after lift-off, a

loss of tail rotor effectiveness that led to the stalling of the tail rotor.

(Paragraph 2.1.9)

57
3.3 Contributing Factors

3.3.1 The pilot lifted off in tailwind, followed by a right turn in the yawing plane.

(Paragraph 2.1.9.6)

3.3.2 The effect of the wind on the tail rotor compounded by the weathercock

effect contributed to the acceleration of the rate of turn to the right in the

yawing plane in the initial 180° of the right turn. (Paragraphs 2.1.9.1,

2.1.9.7, 2.1.9.8 and 2.1.9.9)

3.3.3 The pilot did not adequately appreciate the wind effect associated with the

tailwind hover, and the additional weathercock effect in the subsequent right

yaw turn. (Paragraphs 2.1.9.1, 2.1.9.7, 2.1.9.8 and 2.2.3)

3.3.4 The timing and the magnitude of left yaw pedal input applied by the pilot,

when the helicopter was into wind, to arrest the rapid and increasing rate of

turn inadvertently caused the tail rotor to stall, resulting in LTT.

(Paragraphs 2.1.9.7, 2.1.9.8, 2.1.9.9 and 2.1.9.10)

3.3.5 During the increasing rate of turn to the right, the pilot became disoriented

in the uncontrolled right turns and did not realize that the helicopter might

have experienced a LTT. (Paragraph 2.1.9.11)

58
4. SAFETY RECOMMENDATIONS

4.1 Recommendation 2007-1

It is recommended that the personnel providing helicopter ground school

training should strengthen pilots’ awareness of LTE phenomenon, in

particular the risk associated with a fast uncontrolled spot turn in a LTE

situation, and the possibility of LTE developing into LTT due to the stalling

of the tail rotor. (Paragraphs 3.3.1, 3.3.2, 3.3.3, 3.3.4 and 3.3.5)

4.2 Recommendation 2007-2

It is recommended that the aircraft manufacturer specifies in the R44 POH

the maximum rate of turn permitted for the helicopter in the yawing plane.

(Paragraphs 3.1.24 and 3.3.4)

***

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60
 Appendix A
Simplified Schematic Diagram of the Powerplant and Transmission System of R44 Helicopter
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Intentionally Left Blank

62
 Appendix B
Location of Pak A, Sai Kung in UCARA

Pak A, Sai Kung

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Intentionally Left Blank

64
 Appendix C
Damage to the Helicopter

Helicopter Wreckage (viewed from the rear of the helicopter)

Helicopter Wreckage (viewed from the right rear of the helicopter)

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 Helicopter Wreckage (viewed from the right front of the helicopter)

Helicopter Cabin
(perspex canopy removed by emergency service personnel during rescue operation)

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 Summary of Emergency Handling of the Helicopter Accident on 11 June 2005
Number of Time Alerted Time of Time Taken Task(s) Stand Remarks
Responses Personnel Alerted by Arrival at to Arrive at Involved Down
Attending the Accident the Accident Time
the Accident Site Site
Organizations/Units Site

Kowloon Regional Command - 1417 hrs A member - - Alerting, 1648 hrs The first unit alerted of the accident.

(All times in Hong Kong Local Time)

& Control Centre (RCCC/K) of the Command and
of Hong Kong Police (HKP) public Coordination
Marine Regional Command & - 1418 hrs - - - Alerting, 1648 hrs -

Appendix D
Control Centre (RCCC/M) of Command and
HKP Coordination
Police officers of 9 1418 hrs - 1445 hrs 27 minutes Accident Site 1523 hrs Part of the access to the accident site was
Emergency Unit, Cordoning and via footpath.
Kowloon East, HKP Search
(Police Vehicle EU51)
Marine Police (MarPol) 3 1419 hrs - 1434 hrs 15 minutes Accident Site 1525 hrs PL62 was on duty patrol close to the
officers of Police Launch (PL) Cordoning and accident site at the time of the accident and
PL62, HKP Rescue it arrived off the coast near Pak A at around
1429 hrs from which Police Vessel (PV12)
was launched to take three police officers
onshore to access the accident site.

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 Number of Time Alerted Time of Time Taken Task(s) Stand Remarks
Responses Personnel Alerted by Arrival at to Arrive at Involved Down
Attending the Accident the Accident Time
the Accident Site Site
Organizations/Units Site

MarPol officers of 4 1419 hrs - 1445 hrs 26 minutes On-scene 1650 hrs PL55 was the MarPol on-scene command
Police Launch PL55, HKP Command and unit from which PV65 was launched to take
Coordination four police officers onshore to access the
accident site.
MarPol officers of 2 1419 hrs - 1447 hrs 28 minutes Accident Site 1520 hrs PL30 was tasked at 1436 hrs and it arrived
Police Launch PL30, HKP Cordoning and off Pak A around 1440 hrs. Two police
Rescue officers were dispatched from the launch at
1442 hrs to access the accident site.
Fire Services Communication - 1419 hrs RCCC/K - - Alerting, 1648 hrs -
Centre (FSCC) of Fire Command and
Services Department (FSD) Coordination
Duty Aerodrome Supervisor, - 1420 hrs FSCC & - - Alerting and 1648 hrs Once alerted by FSCC, the Duty
Air Traffic Control Tower, RCCC/M Coordination Aerodrome Supervisor tasked a GFS
Civil Aviation Department helicopter (Helicopter 86) that was
(CAD) operating near Pak A to proceed to scene to
verify the accident.

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 Number of Time Alerted Time of Time Taken Task(s) Stand Remarks
Responses Personnel Alerted by Arrival at to Arrive at Involved Down
Attending the Accident the Accident Time
the Accident Site Site
Organizations/Units Site

Air Command Control Centre - 1421 hrs RCCC/M - - Command and 1648 hrs -
(ACCC) of Government Coordination
Flying Service (GFS)

Fire services & ambulance 20 1422 hrs - *1520 hrs *58 minutes Rescue and 1608 hrs Some of the personnel accessed the
officers of FSD (including 3 (*arrival of Casualty accident site via footpath while others were
(other than Sai Kung Station) ambulance the first Evacuation transported to the scene by Police launch or
units) batch) GFS helicopter.
Police officers of 11 1424 hrs - 1448 hrs 24 minutes Accident Site Afternoon Part of the access to the accident site was
Sai Kung Division, HKP Cordoning and on 12 June via footpath.
Rescue 2005 (Note: The wreckage was guarded until its
removal in the afternoon on 12 June 2005)
Commanding officers of 3 1424 hrs - 1501 hrs 37 minutes On-Scene 1645 hrs Part of the access to the accident site was
Sai Kung Division, HKP Command via footpath.
Fire services officers of 15 1426 hrs - 1501 hrs 35 minutes Rescue 1608 hrs Part of the access to the accident site was
Sai Kung Station, FSD via footpath.

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 Number of Time Alerted Time of Time Taken Task(s) Stand Remarks
Responses Personnel Alerted by Arrival at to Arrive at Involved Down
Attending the Accident the Accident Time
the Accident Site Site
Organizations/Units Site

Crew of Helicopter 86, 4 1427 hrs Control 1432 hrs 5 minutes Rescue and 1524 hrs Helicopter 86 was tasked by the Duty
GFS (2 pilots + 2 Tower, Casualty Aerodrome Supervisor in the Control Tower
crewmen) CAD Evacuation to join the rescue operation whilst engaging
in other flying duty. It was the first
emergency service unit that arrived at the
accident scene, and it airlifted the first
injured person to arrive Pamela Youde
Nethersole Eastern Hospital (PYNEH) at
1454 hrs.
Helicopter 83, GFS 6 - - 1450 hrs 20 minutes Casualty 1531 hrs Helicopter 83 departed GFS base at 1430
(Crew + Medical Team) (2 pilots + 2 (flight time) Evacuation hrs and arrived the scene at 1450 hrs. It
crewmen and then departed Pak A at 1459 hrs with the
1 doctor + second injured person and arrived PYNEH
1 nurse) at 1504 hrs.

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 Number of Time Alerted Time of Time Taken Task(s) Stand Remarks
Responses Personnel Alerted by Arrival at to Arrive at Involved Down
Attending the Accident the Accident Time
the Accident Site Site
Organizations/Units Site

Crew of Helicopter 47, 2 - - 1528 20 minutes Casualty 1551 hrs Helicopter 47 departed GFS base at 1508
GFS (1 pilot + 1 (flight time) Evacuation hrs and arrived the scene at 1528 hrs. It
crewman) then departed Pak A at 1541 hrs with the
third (last) injured person and arrived
PYNEH at 1546 hrs.
Crew of Fixed-Wing Aircraft 2 pilots - - - - Air Command 1549 hrs Rescue 38 was tasked to join the rescue
(Jetstream) Rescue 38, and operation whilst engaging in other local
GFS Coordination flying duty. It reported in Sharp Peak area
near the accident scene at 1445 hrs, and
assisted the rescue operation by keeping
other emergency units informed of the
development on scene.
Commanding officers of 2 1428 hrs - 1503 hrs 35 minutes On-Scene 1608 hrs Part of the access to the accident site was
New Territories East Division, Command via footpath.
FSD

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 Number of Time Alerted Time of Time Taken Task(s) Stand Remarks
Responses Personnel Alerted by Arrival at to Arrive at Involved Down
Attending the Accident the Accident Time
the Accident Site Site
Organizations/Units Site

Hospital Authority - 1433 hrs FSCC - - To alert 1648 hrs All three injured persons were airlifted by
hospitals GFS helicopter to PYNEH where the first
injured person arrived at 1454 hrs.
Pamela Youde Nethersole - 1448 hrs RCCC/M - - Medical 1552 hrs Took over the last injured person from GFS
Eastern Hospital (PYNEH) Service to helicopter at approximately 1547 hrs.
Injured Persons

Notes:

1. The Regional Command & Control Centre, Kowloon (RCCC/K) of the Hong Kong Police (HKP) was the first emergency service unit notified of the helicopter
accident at 1417 hrs by a member of the public at Pak A through emergency telephone line ‘999’.
2. The Fire Services Communication Control Centre (FSCC) of the Fire Services Department (FSD) informed the Duty Aerodrome Supervisor of the Civil Aviation
Department of this accident at 1420 hrs. The Aerodrome Supervisor thence took alerting actions as per standard procedures and tasked a GFS helicopter (Helicopter
86), which was operating in the vicinity of Pak A at the time, to proceed to scene to verify the accident.
3. Helicopter 86 confirmed the accident and landed at an open area near the accident site at 1432 hrs. Two crewman officers approached the wreckage and found three
injured persons on scene.
4. Three Marine Police officers deployed from Police Launch (PL62) arrived the scene at 1434 hrs, followed by more HKP and FSD officers arriving within the next 30
minutes in batches.

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5. Apart from one passenger who was uninjured in the accident, the pilot and two passengers sustained spine injuries, and they were subsequently airlifted via three
separate GFS helicopter flights to Pamela Youde Nethersole Eastern Hospital (PYNEH). Details on the rescue and injured persons are as follows:

Details of Injured Persons Time of Accident Time of Airlift from Time of Arrival Time of Time Admitted to
Accident Scene PYNEH Registration Ward
Pilot; male; spine injury 1412 1449 1454 1503 1533
Passenger; female; spine injury 1412 1459 1504 1510 1550
Passenger, female; spine injury 1412 1541 1546 1554 1625

6. The passenger at the rear left seat who was injured in the accident decided to remain in the helicopter cabin until being attended to by the rescue personnel. It took the
FSD personnel approximately 1 hour and 18 minutes to cut off the roof of the cabin and evacuate her out of the wreckage to the GFS helicopter for airlift to PYNEH.
7. All three injured persons were provided with on-scene medical treatment to stabilize their injuries before airlift to hospital by helicopter.
8. PYNEH was given prior notice about the accident and the take-over of the injured persons from the GFS helicopter was satisfactory.
9. A total of 29 Police officers, 37 FSD officers (including ambulance officers) and 14 GFS officers (including pilots, crewmen and medical personnel) attended to the
accident.
10. On-scene commands were satisfactorily effected and coordinated by the HKP and FSD officers concerned.
11. Rescue equipment and means of communication used by various emergency service units in this accident were effective.
12. The injured persons were satisfied with the services provided by the emergency service units concerned.

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74
 Appendix E
Letter Issued by CAD in January 2004 on
UKCAA Flight Operations Department Communication 1/2004

[Name Intentionally Deleted]

75
76
77
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 Appendix F
Emergency Procedures for Loss of Tail Rotor Thrust during Hover

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