FLIGHT MANUAL BK 117 C-2

AUTOMATIC FLIGHT CONTROL SYSTEM (AFCS)

4 NORMAL PROCEDURES
The complete AFCS is powered up by setting the avionic master switches to ON, as
mentioned in para 4.4.3 of the basic Flight Manual BK 117 C–2.

EFFECTIVITY ASB BK117C–2–22A–012 (up to and including AFCS software version

416-00297-202)

CAUTION IF THE PILOT USES THE “ALT.A“ MODE OF THE AFCS THE PILOT HAS
TO MONITOR THE ALTITUDE. IF THE AUTOPILOT DOES NOT LEVEL–
OFF (AS DESCRIBED IN THE ASB MENTIONED ABOVE) AT THE
DESIRED ALTITUDE THE PILOT HAS TO PRESS THE “ALT“ MODE
SELECTOR SWITCH ON THE APMS PANEL TO DISENGAGE “ALT“
MODE THAT WAS ERRONEOUSLY TRIGGERED. WHEN REACHING
THE DESIRED ALTITUDE, PILOT HAS TO PRESS THE “ALT“ MODE
SELECTOR SWITCH AGAIN TO ENGAGE “ALT“ MODE AND LEVEL–OFF
AT CURRENT ALTITUDE.

EFFECTIVITY All

4.1 PREFLIGHT CHECK

NOTE D The entire system preflight check has to be performed prior to the first flight of
the day (once a day). However, if for emergency reasons, the pilot wishes to
interrupt the preflight test he should do so using the SAS/AP CUT OFF
button.
D Perform peripheral checks and system test in conjunction with the normal
preflight after completion of hydraulic checks, with both engines in IDLE and
mast moment trimmed to minimum.
D During the system test routine the helicopter should not be moved nor should
the pilot move or even touch the controls or the APMS as this may cause false
errors to be detected by the computer (the cyclic stick will move of itself while the
computer performs the test cycle).

4.1.1 Peripheral checks

Transponder – TEST, then SBY

4.1.2 AFCS preflight check (both engines in idle)

WARNING IF A FAILURE IS DETECTED DURING PREFLIGHT CHECK MAINTENANCE

ACTION IS NECESSARY.

NOTE The system test is initiated with autopilot off, collective full down and locked and
cyclic stick in neutral position.

TEST pb on APMS – Press to initiate system test

(TEST and AP1 pb start blinking)
Warning panel – Check AP warning light illumi-
nated

EASA APPROVED
Rev. 7 9.2-1 – 71
The document reference is online, please check the correspondence between the online documentation and the printed version.
FLIGHT MANUAL BK 117 C-2

AUTOMATIC FLIGHT CONTROL SYSTEM (AFCS)

PFD – Check all AFCS–related indica-

tions in red, afterwards:

CAD – Check the following caution indi-

cations during AP1 system test :
– AP1
– TRIM
– ACTUATOR
– BACKUP SAS
– AHRS DISC
During AP2 system test (AP2 pb
blinking) the AP2 caution indica-
tion appears instead of AP1, to-
gether with all other above men-
tioned caution indications
Cyclic stick and pedals – Check small motion during AP1
system test and again during
AP2 system test
If system test was successful (TEST pb extinguishes and AP1/AP2 pb are permanently
illuminated on APMS ):
CAD – Check advisory AP TEST OK
AP1 and AP2 pb on APMS – Press to engage AFCS (“OFF” il-
lumination of the pb extinguishes)

If system test was not successful (TEST pb remains permanently illuminated indicating ma-
jor failure, or continues blinking indicating minor failure):

CAD – Check corresponding caution in-

dication
TEST pb – Press to acknowledge test result
AFCS – Not (completely) available

If system test failed, perform the following checks and repeat testing:

Collective lever – Check down

Cyclic stick and pedals – Check in neutral position and
free movement
Hydraulic pressure – Within requirements
If a failure is detected by the test and persists, maintenance action is necessary.

EASA APPROVED
9.2-1 – 72 Rev. 7
The document reference is online, please check the correspondence between the online documentation and the printed version.
 FLIGHT MANUAL BK 117 C-2

AUTOMATIC FLIGHT CONTROL SYSTEM (AFCS)

4.1.3 AFCS and backup SAS cut off pb preflight check (both engines in idle)

AP1 and AP2 pb on APMS – Press to engage AFCS

(“OFF” illumination of the pb ex-
tinguishes)
SAS/AP CUT pb on cyclic stick – Push
CAD – Check caution indication:
BACKUP SAS + YAW SAS*
PFD – Check axial letter indication in
red, afterwards:
OFF OFF

SAS ON sw on cyclic stick – Push forward

CAD – Check caution indication
BACKUP SAS + YAW SAS*
disappeared
Perform check in the same manner by using SAS/AP CUT pb on copilot’s cyclic stick in the
case that dual controls (FMS 9.2–7) are installed.

(* YAW SAS caution indication only for H/C S/N 9034 or subsequent or after SB MBB–
Bk117C–2–22–002).

4.2 OPERATION

NOTE This section contains information and procedures only for typical operations of the
autopilot, i. e. the sequence of AFCS mode applications shown in the following is
not mandatory.
For system performance and functional principles refer to section 7 of this FMS.

4.2.1 Before takeoff

SAS ON sw – Press to engage backup SAS

(BACKUP SAS + YAW SAS*
caution must not be on)

NOTE The backup SAS + YAW SAS* must be engaged before the autopilots

AP1 and AP2 pb on APMS – Press to engage AFCS

(“OFF” illumination of the pb ex-
tinguishes)
(* YAW SAS caution indication only for H/C S/N 9034 or subsequent or after SB MBB–
Bk117C–2–22–002).

EASA APPROVED
Rev. 7 9.2-1 – 73
The document reference is online, please check the correspondence between the online documentation and the printed version.
FLIGHT MANUAL BK 117 C-2

AUTOMATIC FLIGHT CONTROL SYSTEM (AFCS)

4.2.2 Takeoff and climbout

For engagement of HDG mode:

When IAS above 60 kts:

HDG rotary pb on APMS – Turn and set heading bug on

FCDS if necessary, press to ac-
tivate heading bug (triangle next
to the rotary pb illuminates green)
NOTE Engagement of NAV, VOR, VOR.A or LOC mode disengages HDG mode.

For climbout using IAS mode:

Desired airspeed for climbout – Establish

IAS pb on APMS – Press to engage IAS mode
(pb illuminates green: “ON”)

NOTE Engagement of ALT, ALT.A, VS, GA or GS mode disengages IAS mode.

For climbout or descent using VS mode:

Desired vertical speed – Establish

VS pb on APMS – Press to engage VS mode
(pb illuminates green: “ON”)

NOTE If the helicopter descends too low, the AFCS automatically reverts to ALT mode,
levelling off at approx. 65 ft above ground.
Engagement of IAS, ALT, ALT.A, GA or GS mode disengages VS mode.

For climbout using ALT.A mode:

ALT.A rotary pb on APMS – Rotate to preselect the desired

altitude, then press to engage al-
titude acquisition (triangle next to
the rotary pb illuminates green)
NOTE 300 ft before reaching the selected altitude the AFCS automatically reverts to ALT
mode. Engagement of IAS, ALT, VS, GA or GS mode disengages ALT.A mode.

EASA APPROVED
9.2-1 – 74 Rev. 7
The document reference is online, please check the correspondence between the online documentation and the printed version.
 FLIGHT MANUAL BK 117 C-2

AUTOMATIC FLIGHT CONTROL SYSTEM (AFCS)

4.2.3 Enroute operation

For ALT mode

Transition to cruising flight after climbout with IAS or VS mode:

Collective lever – Adjust for level flight after reach-

ing desired altitude
IAS or V/S pb on APMS – Press to disengage respective
mode
ALT pb on APMS – Press to engage ALT mode
(pb illuminates green: “ON”)

NOTE Engagement of IAS, ALT.A, VS, GS or GA mode disengages ALT mode.

When IAS or ALT mode is selected the respective reference values will be marked with green
triangles on the FCDS.
To alter reference values use the HDG rotary pb for heading and the BEEP TRIM sw on the
cyclic stick for airspeed and altitude.

For VOR.A mode:

Used to capture and track a desired course i.e. to track TO or FROM VOR station (typically 10
nm from the beacon):

MASTER sw on RCU – Select VOR source (nominal is

VOR 1 for copilot, VOR 2 for pilot)
Navigation receiver – Set desired VOR frequency
CRS rotary knob on ICP – Set course pointer to desired
VOR track/radial
APP pb on APMS – Press (pb illuminates amber: “A”)

For VOR radial/track interception (if HDG mode is required for intersection):

HDG rotary pb on APMS – Rotate to set heading bug to the

VOR radial/track interception
course on FCDS, then press to
engage mode (triangle next to
the rotary pb illuminates green)

NOTE D As the helicopter nears the selected VOR radial/track, the AFCS automatically
disengages APP arm and HDG (if it is engaged). The APP “C” caption
illuminates green on the APMS, indicating VOR radial/track capture and the
helicopter turns onto the radial/track.

D Selection of the DME to a station other than the active VOR station is not
recommended because VOR.A mode performance may then be degraded

For NAV (VOR) mode:

EASA APPROVED
Rev. 7 9.2-1 – 75
The document reference is online, please check the correspondence between the online documentation and the printed version.
FLIGHT MANUAL BK 117 C-2

AUTOMATIC FLIGHT CONTROL SYSTEM (AFCS)

Used to capture and track a desired course i.e. to track TO or FROM VOR station:

NOTE D For short distance navigation to a VOR station the use of VOR.A mode is
recommended (see previous page).

D Selection of the DME to a station other than the active VOR station is not
recommended because VOR mode performance may then be degraded

The operating procedure for NAV (VOR) mode is the same as for VOR.A mode (see previous
page), except for the use of the NAV pb instead of the APP pb on APMS.

For NAV (NAV) mode:

Used in combination with a navigation management system (NMS – refer to FMS 9.2–17),
where available, issuing a pure roll steering command to the AFCS:

NMS – Select suitable navigation mode

such as GPS, DME/DME or
VOR/DME.
MASTER sw on RCU – Select master side for the sensor
ICP – Select NMS as navigation
source for AFCS
NAV pb on APMS – Press (pb illuminates green: “C”)

EASA APPROVED
9.2-1 – 76 Rev. 7
The document reference is online, please check the correspondence between the online documentation and the printed version.
 FLIGHT MANUAL BK 117 C-2

AUTOMATIC FLIGHT CONTROL SYSTEM (AFCS)

4.2.4 Approach

APP (LOC) mode:

Used to capture and track the inbound front course of a localizer for runway approach:

MASTER sw on RCU – Select LOC source (nominal is

LOC 1 for copilot, LOC 2 for pilot)
Navigation receiver – Set desired LOC frequency
CRS rotary knob on ICP – Set course pointer on ND for
LOC course in order to define
the intersection angle with
respect to heading
APP pb on APMS – Press (pb illuminates amber: “A”)

For LOC inbound front course interception:

HDG rotary pb on APMS – Rotate to set heading bug to the

LOC radial interception course
on ND, then press to engage
mode (triangle next to the rotary
pb illuminates green)

NOTE As the helicopter nears the selected LOC radial, the AFCS automatically
disengages APP arm and HDG (if it is engaged). The APP “C” caption illuminates
green on the APMS, indicating LOC radial capture and the helicopter turns onto
the LOC radial.
4.2.5 Landing

All landings:
– press FTR switch until full touchdown or
– switch CYC and YAW TRIM OFF.

Slope landing: Ground oscillations in roll axis may be encountered. Pressing the FTR switch
should damp out these oscillations.

EASA APPROVED
Rev. 7 9.2-1 – 77
The document reference is online, please check the correspondence between the online documentation and the printed version.
FLIGHT MANUAL BK 117 C-2

AUTOMATIC FLIGHT CONTROL SYSTEM (AFCS)

GS mode (provides in combination with APP(LOC) mode an ILS approach):

The GS mode acquires and holds the selected glide slope in order to perform an ILS
approach to an airport. At approx. 65 ft above ground, the AFCS automatically reverts to ALT
mode to level off the helicopter.

MASTER sw on RCU – Select ILS source (nominal is

ILS 1 for copilot, ILS 2 for pilot)
Navigation receiver – Set desired ILS frequency

Perform all actions to arm and/or engage APP(LOC) mode with the desired heading
intersection angle (optionally supported by HDG mode) as described on previous page.

GS pb on APMS – Press (pb illuminates amber: “A”)

The AFCS is now armed for au-
tomatic capture of the glide slope.

Upon ILS/LOC capture, the AFCS automatically disengages APP arm and HDG (if it is
engaged). The APP “C” caption illuminates green on the APMS.

Upon ILS/GS capture, the AFCS automatically disengages GS arm and any previously
activated pitch mode. The GS “C” caption illuminates green on the APMS.

Recommended values for an ILS approach:

Interception angle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45_

LOC interception distance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 nm

Airspeed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80–125 kts

Max. crosswind . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 kts

GA mode (to abort an approach):

The GA (go around) mode, used in case of a missed approach, acquires and holds a
pre–defined vertical speed of 1000 ft/min.

GA pb on collective grip – Press (VS pb on APMS illumi-

nates green: “ON”)

NOTE D After 10 seconds, GA mode automatically reverts to VS mode.

D An initial altitude loss of up to 60ft may be encountered after engaging GA

mode.

D Engagement of ALT, ALT.A, VS or IAS mode disengages GA mode.

D Below 60 kts IAS and with IAS mode engaged use of the GA mode is
prohibited.

EASA APPROVED
9.2-1 – 78 Rev. 7
The document reference is online, please check the correspondence between the online documentation and the printed version.