Air Accidents Investigation Branch

Annual Safety Review 2022 AAIB

Air Accidents Investigation Branch

Grumman AA-5, G-BBSA

25 September 2021, Teesside International Airport

Synopsis

The aircraft suffered a partial loss of engine power

very shortly after takeoff from Runway 23 at
Teesside International Airport. The pilot, believing
the aircraft was outside the airport boundary,
attempted a turnback to the airport to land. The
aircraft stalled during the turn and struck the ground
west of the runway near the Runway 05 threshold.
The three occupants all sustained serious injuries.

The engine suffered a partial loss of power during Missing accelerator pump discharge
takeoff due to a portion of the accelerator pump tube from G-BBSA carburettor
discharge tube having been released from the
carburettor into the No 4 cylinder. Following this partial loss of power at low altitude the pilot
decided to turn back to land, although post-accident analysis of the circumstances shows
there was a sufficiently clear area ahead in which to effect a landing. During the turn, at
a low airspeed, the aircraft stalled and struck the ground. All three occupants sustained
serious injuries in the impact.

Management of a partial power loss event is not covered in the PPL syllabus and there is
limited information provided for pilots conducting renewal or revalidation of licences. Three
Safety Recommendations are made to address these topics. Safety action is also being
taken by the CAA

Safety action

• The CAA has agreed to discuss the airworthiness concerns relating to discharge
tube release events with the FAA, who are the regulator of the engine’s Type
Certificate holder.
Safety Actions
Overview

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Edge 540, G-EDGY

1 May 2021, overhead Tempsford Airfield (disused), Bedfordshire

Synopsis

During an aerobatic flight, as the pilot applied a full left

aileron control input, the centre hinge attachment for
the right aileron failed. This allowed the right aileron
to bend up in the centre and fail before detaching from
the aircraft; only a small inboard section of the aileron
remained attached. The pilot had sufficient control
remaining to make a safe landing.

The investigation found that the centre hinge

attachment for the right aileron failed due to fatigue
cracks developing to such an extent that the parts
were no longer able to carry the required load. These
fatigue cracks had multiple origins indicating that they
were not due to a material feature or flaw. The aircraft
manufacturer has issued a Service Letter to all known
Parts of the failed centre hinge
owners recommending regular detailed inspections attachment for the right aileron
of similar aileron centre hinge attachments. The LAA before removal from wing
has contacted all affected owners in the UK to ensure
they are aware of this mandatory Service Letter.

Safety actions

• The aircraft manufacturer has issued Service Letter, SB E540015 to all known
owners of affected aircraft. This letter is annotated ‘MANDATORY’ and recommends
removal of the centre aileron hinge attachment assemblies at each 100 hour or
annual inspection to allow inspection for cracks using a dyepenetrant method.

• The LAA has contacted all affected owners in the UK to ensure they are aware of
this mandatory Service Letter.
Safety Actions
Overview

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Supermarine Aircraft Spitfire Mk 26, G-CIEN

12 August 2021, Newtownards Airport, County Down

Synopsis

After landing, the aircraft suddenly

veered to the right causing the left
wingtip, propeller, and engine cowl
to scrape the runway. Examination
of the left landing gear leg revealed
a failed weld that had allowed the
lower part of the leg to rotate and
consequently affect the wheel
alignment. It is possible that
the weld was damaged during a
Landing gear damage
previous heavy landing, but due (photograph used with permission)
to the design of the leg it had not
been possible to inspect the weld.
The LAA has issued a warning to
owners and is reviewing the design
of the landing gear.

Safety actions

As a result of this accident the following safety actions have been taken:

• The LAA has issued a warning to all UK owners of Spitfire Mk 26 aircraft that there
is potential for hidden damage to a weld following a heavy landing.

• The LAA is reviewing of the design of the Spitfire Mk 26 undercarriage leg, including
the access restriction to inspect the weld that failed.

Safety Actions
Overview

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Europa, G-FLOR
23 June 2021, Brinkworth, Wiltshire

Synopsis

The pilot was on a local flight from Cotswold

Airport with a passenger. The aircraft was flying
at approximately 100 kt and 2,500 ft amsl when,
without warning, the left cockpit door detached.
After checking that the aircraft’s control responses
appeared normal, the pilot returned to Cotswold
where the aircraft landed without further incident.
Subsequent inspection of the left tailplane identified
minor damage to the leading edge and upper surface
consistent with it having been struck by the door.

This was the eighth event involving the inadvertent Rear shoot bolt guide
opening of cockpit doors fitted to Europa aircraft
operated in the UK. The Light aircraft Association (LAA) have developed and issued a
modification to the Europa to prevent the door latch lever reaching the closed position when
the door is not properly latched.

Safety action

• On 1 November 2021, the LAA approved and issued a standard modification

(mod number SM 15833) for fitment to Europa aircraft to prevent the door latch
from closing when the door is not pulled home at the rear, and the rear pin is
properly engaged. The requirement for this modification has been promulgated by
LAA Airworthiness Information Leaflet MOD/247/012, which has been allocated
mandatory status for all Europa aircraft operating under an LAA Permit to Fly
and is required to be fitted within five flying hours after that date, or next permit
revalidation, whichever comes first.
Safety Actions
Overview

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Eurofox 912(S), G-CGYG

29 May 2021, Highland Gliding Club, Easterton Airfield, Elgin, Moray

Synopsis

During the third landing following the replacement of

the nosewheel tyre, the nosewheel detached from the Nose leg fork
aircraftand
Nosewheel andfairing
the nose leg fork dug into the soft ground.
The nose leg broke and the aircraft flipped over onto
its roof causing substantial damage. The investigation
determined that the nosewheel had not been refitted
correctly to the aircraft following the tyre change.

Three safety actions have been taken by the

manufacturer and the LAA.

Safety actions

The followingGround mark have been taken by

safety actions
fromand
the manufacturer nose
theleg
LAA: Remains of nose leg

• The manufacturer will amend Section 5 of

the AMM to include the procedure to refit the Snapped nose leg
nosewheel and to highlight the potential for
clamping the wheel onto the nose leg without
correctly routing the wheel axle through the
nose leg fork.

• The LAA has produced an Engineering Matters article in their monthly Light
Aviation magazine highlighting the potential to incorrectly fit the Eurofox 912(S) 3K
nosewheel.

• The LAA has updated the aircraft’s Type Acceptance Data Sheet, (TADS) 376, to
include reference to an incorrectly fitted nosewheel in paragraph 3.4 – ‘Special
Inspection Points.’
Safety Actions
Overview

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Aeronca 65C, G-BTRG

21 October 2021, Birchwood Airfield, North Yorkshire

Synopsis

Shortly after takeoff the propeller departed the aircraft

and then the engine over sped. All six propeller bolts
failed in fatigue due to a lack of pre-load. It is possible
that a misinterpretation of an engine manufacturer’s
requirement resulted in the incorrect bolt length being
chosen. When the bolts were tightened to the correct
torque they shanked, no pre-load was applied and
failed due to normal propeller loads in fatigue. The
aircraft was extensively damaged and the propeller
was not recovered.
Close-up of propeller flange
Safety action

The engine manufacturer has taken the following safety action:

• To revise the propeller installation document to include a drawing to aid the correct
length of propeller bolt to be selected.
Safety Actions
Overview

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General Aviation (Gliders)

Silent 2 Electro, G-CIRK

23 April 2021, Wormingford Airfield, Colchester, Essex

Synopsis

During the ground roll for a

self-launched takeoff, the motor
glider suffered a propeller strike
shortly before it got airborne. The
eyewitness evidence and recorded
data showed that the glider climbed
steeply to about 100 ft before stalling
and entering an incipient spin to the
left. The glider struck the ground
nose-first and the pilot suffered
serious injuries, in part due to the lack Damage to aircraft
of energy absorbing structure ahead
of the pilot’s seat. The pilot had no recollection of the accident flight. No mechanical fault
or defect was found that would explain the aircraft pitching up excessively after takeoff.
The steep climb was most likely the result of an excessive aft stick input that was not
corrected.

While the investigation could not positively identify the cause of the aft stick input, it is likely
that distraction, pilot workload or stress were factors in the accident. Additional contributory
factors were the aircraft’s characteristics of low stick forces with low sensory feedback, and
poor stall warning indications.

As a result of the investigation findings the British Gliding Association (BGA) has published
and sent a ‘Safety Briefing’ to Silent 2 Electro owners in the UK which provides guidance
on operating the motor gilder. This has also been provided to the European Gliding Union
(EGU) for onward dissemination to other European gliding associations.

Safety actions

• The BGA has published and sent a ‘Safety Briefing’ to Silent 2 Electro owners in
the UK and to the EGU which provides guidance on operating the Silent 2 Electro
(Appendix A). It covers ways to address the aircraft’s stick force characteristics,
Safety Actions

its stall characteristics, recommendations on takeoff handling, takeoff flap and

Overview

takeoff speeds, as well as recommendations on mentally rehearsing aborted

takeoffs.

• On 24 January 2022 the CAA updated G-INFO to show when an aircraft is fitted
with an Emergency Ballistic Device, such as a Ballistic Parachute Recovery
System (BPRS), an active ejector seat or canopy miniature detonating cord.
The CAA undertook the task of identifying UK-registered aircraft fitted with

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such devices to support this change. To capture newly-registered aircraft with

an Emergency Ballistic Device in the future, the CAA is updating the aircraft
registration process to specifically require owners to declare the aircraft status
with respect to an Emergency Ballistic Device.

• The CAA are planning to contact the registered owners of Single Seat Deregulated
(SSDR) aircraft, which are fitted with a BPRS device, to inform them about Sky
Wise article SW2021/91 which strongly recommends that owners of these aircraft
comply with the requirements of British Civil Airworthiness Requirement (BCAR)
Section S, Sub-Section K, to clearly identify the presence of the BPRS.
Safety Actions
Overview

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Unmanned Air Systems

Avy Aera 1.5

6 May 2022, Lamlash, Isle of Arran

Synopsis

The Unmanned Aircraft (UA) was hovering

at between 50 m to 65 m agl during a
demonstration flight, when a rhythmic, lower
than normal sound was heard emanating
from the UA. It then dipped and spiralled
downwards during which control could not be
re-established. The UA hit the ground and
was severely damaged. A fatigue failure of
a blade attachment bolt caused one of the lift
propeller blades to detach in flight.

Safety actions

As a result of this accident the following Avy Area 1.5 in flight

safety actions have been taken: (image courtesy of manufacturer)

• The manufacturer has introduced a 10-hour replacement schedule for the propellers
and immediate propeller replacement if a Quadchute1 event occurs.

• The manufacturer is carrying out a review of propeller designs for UAs under its
development.

Safety Actions
Overview

Footnote

1
Quadchute: if fixed-wing mode fails (eg loss of altitude), multicopter mode takes over and brings the aircraft
to a steady hovering position.

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Evolve Dynamics Sky Mantis

1) 14 January 2021, Skegness, Lincolnshire
2) 17 February 2021, Skegness, Lincolnshire

Synopsis

A screw which attached the propeller blade

of an unmanned aircraft (UA) to the motor
hub adaptor failed during a training flight. A
second screw failure was experienced by
the same operator after the UA had been
repaired and had been fitted with a different
design of hub adaptor and screws.

The first failure was caused by stress

corrosion cracking possibly with the
presence of hydrogen embrittlement. The Evolve Dynamics Sky Mantis
second was a fatigue failure which may
have been initiated and accelerated by hydrogen embrittlement. The hardness of both
screws exceeded the specification which increased the susceptibility of the screws to
hydrogen embrittlement.

The UA manufacturer has introduced several design changes to prevent reoccurrence.

Safety actions

As a result of these two events the manufacturer has made several design changes to
the motor hub adaptor.

• Introduced changes to the hub assembly by;

- Increasing the screw diameter to M4

- Using a serrated washer

- Using a single use lock nut

- Removal of the thread locking compound

- Adding a brass spacer to the blade root

Safety Actions

• Incorporated a stress test to ensure that bolts do not suffer from hydrogen
Overview

embrittlement

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MA Scale F4 Phantom
16 September 2021, near Kenyon Hall Farm Airfield, Warrington, Cheshire

Synopsis

A turbine powered model aircraft suffered a Accident site

loss of control during its maiden test flight. Railway track

It continued to fly beyond visual line of sight

before crashing on a railway track and was
subsequently run over by a passing train. Footpaths
Model flying runways

Safety actions taken as a result of this

accident include publication of enhanced
guidance for members by the British Model
Flying Association (BMFA). The model
Runway 05/23
flying club also amended its procedures Footpaths

relating to flying turbine powered models.

Safety actions Airfield overview

• Following the accident, collaboration was undertaken between the BMFA and
Network Rail’s Air Operations team. This resulted in the provision of tailored
guidance for unmanned and model aircraft operators which will be incorporated in
the BMFA’s member’s handbook. It included the provision of a 24-hour emergency
contact telephone number for reporting railway safety threats, including the
presence of people or objects on or near railway tracks.

• The BMFA also published an article about this accident, and operation in proximity
to railways in general, in the July 2022 edition of its member magazine ‘BMFA
news’.

• In addition, the BMFA has updated its incident/accident reporting portal to specifically
guide members to telephone Network Rail immediately in the event that an aircraft
has come down on Network Rail property, in addition to the requirement to inform
the AAIB.

• After the accident the club amended its procedures to require any turbine powered
model to be approved by the club committee before it can be flown at the site, so
that its suitability can be assessed. Following this investigation the club added a
section to its procedures relating to retrieval of models that land outside the airfield
boundary, which directly references the Network Rail 24hour emergency telephone
Safety Actions

number.
Overview

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Appendix 1
Commercial Aviation Safety Team (CAST) / ICAO Common Taxonomy
Team (CICTT) Occurrence Categories
CODE DESCRIPTION
ARC ABNORMAL RUNWAY CONTACT
AMAN ABRUPT MANEUVER
ADRM AERODROME
MAC AIRPROX/TCAS ALERT/LOSS OF SEPARATION/NEAR MIDAIR COLLISIONS/
MIDAIR COLLISIONS
ATM/CNS AIR TRAFFIC MANAGEMENT/COMMUNICATIONS NAVIGATION OR
SURVEILLANCE
BIRD BIRD
CABIN CABIN SAFETY EVENTS
CTOL COLLISION WITH OBSTACLE(S) DURING TAKEOFF AND LANDING
CFIT CONTROLLED FLIGHT INTO OR TOWARD TERRAIN
EVAC EVACUATION
EXTL EXTERNAL LOAD RELATED OCCURRENCES
F–NI FIRE/SMOKE (NON-IMPACT)
F–POST FIRE/SMOKE (POST-IMPACT)
FUEL FUEL RELATED
GTOW GLIDER TOWING RELATED EVENTS
GCOL GROUND COLLISION
RAMP GROUND HANDLING
ICE ICING
LOC–G LOSS OF CONTROL – GROUND
LOC–I LOSS OF CONTROL – INFLIGHT
LOLI LOSS OF LIFTING CONDITIONS EN ROUTE
LALT LOW ALTITUDE OPERATIONS
MED MEDICAL
NAV NAVIGATION ERRORS
OTHR OTHER
RE RUNWAY EXCURSION
RI RUNWAY INCURSION
SEC SECURITY RELATED
SCF–NP SYSTEM/COMPONENT FAILURE OR MALFUNCTION (NON-POWERPLANT)
SCF–PP SYSTEM/COMPONENT FAILURE OR MALFUNCTION (POWERPLANT)
TURB TURBULENCE ENCOUNTER
USOS UNDERSHOOT/OVERSHOOT
UIMC UNINTENDED FLIGHT IN IMC
UNK UNKNOWN OR UNDETERMINED
WILD WILDLIFE
WSTRW WIND SHEAR OR THUNDERSTORM

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Glossary of Abbreviations used in AAIB Reports

aal above airfield level EAS equivalent airspeed

ACAS Airborne Collision EASA European Union Aviation
Avoidance System Safety Agency
ACARS Automatic Communications ECAM Electronic Centralised
And Reporting System Aircraft Monitoring
ADF Automatic Direction Finding EGPWS Enhanced GPWS
equipment EGT Exhaust Gas Temperature
AFIS(O) Aerodrome Flight EICAS Engine Indication and Crew
Information Service (Officer) Alerting System
agl above ground level EPR Engine Pressure Ratio
AIC Aeronautical Information ETA Estimated Time of Arrival
Circular
ETD Estimated Time of Departure
amsl above mean sea level
FAA Federal Aviation
AOM Aerodrome Operating Administration (USA)
Minima
FDR Flight Data Recorder
APU Auxiliary Power Unit
FIR Flight Information Region
ASI airspeed indicator
FL Flight Level
ATC(C)(O) Air Traffic Control (Centre)
(Officer) ft feet
ATIS Automatic Terminal ft/min feet per minute
Information Service g acceleration due to Earth’s
ATPL Airline Transport Pilot’s gravity
Licence GNSS Global Navigation Satellite
BMAA British Microlight Aircraft System GPS
Association GPWS Ground Proximity Warning
BGA British Gliding Association System hours (clock time as
in 1200 hrs)
BBAC British Balloon and Airship
Club HP high pressure
BHPA British Hang Gliding & hPa hectopascal (equivalent unit
Paragliding Association to mb)
CAA Civil Aviation Authority IAS indicated airspeed
CAVOK Ceiling And Visibility OK (for IFR Instrument Flight Rules
VFR flight) ILS Instrument Landing System
CAS calibrated airspeed IMC Instrument Meteorological
cc cubic centimetres Conditions
CG Centre of Gravity IP Intermediate Pressure
cm centimetre(s) IR Instrument Rating
CPL Commercial Pilot’s Licence ISA International Standard
Atmosphere
°C,F,M,T Celsius, Fahrenheit,
magnetic, true kg kilogram(s)
CVR Cockpit Voice Recorder KCAS knots calibrated airspeed
DME Distance Measuring KIAS knots indicated airspeed
Equipment KTAS knots true airspeed
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Glossary of Abbreviations used in AAIB Reports cont

km kilometre(s) QNH altimeter pressure setting to

kt knot(s) indicate elevation amsl
lb pound(s) RA Resolution Advisory
LP low pressure RFFS Rescue and Fire Fighting
Service
LAA Light Aircraft Association
rpm revolutions per minute
LDA Landing Distance Available
RTF radiotelephony
LPC Licence Proficiency
RVR Runway Visual Range
m metre(s)
SAR Search and Rescue
mb millibar(s)
SB Service Bulletin
MDA Minimum Descent Altitude
SSR Secondary Surveillance
METAR a timed aerodrome Radar
meteorological report
TA Traffic Advisory
min minutes
TAF Terminal Aerodrome
mm millimetre(s) Forecast
mph miles per hour TAS true airspeed
MTWA Maximum Total Weight TAWS Terrain Awareness and
Authorised Warning System
N Newtons TCAS Traffic Collision Avoidance
NR Main rotor rotation speed System
(rotorcraft) TODA Takeoff Distance Available
Ng Gas generator rotation UA Unmanned Aircraft
speed (rotorcraft) UAS Unmanned Aircraft System
N1 engine fan or LP compressor USG US gallons
speed UTC Co-ordinated Universal Time
NDB Non-Directional radio (GMT)
Beacon V Volt(s)
nm nautical mile(s) V1 Takeoff decision speed
NOTAM Notice to Airmen V2 Takeoff safety speed
OAT Outside Air Temperature VR Rotation speed
OPC Operator Proficiency Check VREF Reference airspeed
PAPI Precision Approach Path (approach)
Indicator VNE Never Exceed airspeed
PF Pilot Flying VASI Visual Approach Slope
PIC Pilot in Command Indicator
PM Pilot Monitoring VFR Visual Flight Rules
POH Pilot’s Operating Handbook VHF Very High Frequency
PPL Private Pilot’s Licence VMC Visual Meteorological
Conditions
psi pounds per square inch
VOR VHF Omnidirectional radio
QFE altimeter pressure setting Range
to indicate height above
aerodrome

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