-
Main drive shaft failure - The main drive shaft, also
known as the barbell shaft, connects the engine to the transmission. It
has a flexible splined coupling on each end, giving it its name. The aft
end is connected to the freewheeling unit. Then the shaft passes through
the firewall and connects to the transmission input pinion. Failure of
this shaft would unload the freewheeling compressor and leave the rotor
transmission, and consequently, the rotor, underpowered. [Systems
4-6]
-
Engine restart in flight - An engine restart in flight
would most likely result from a malfunction of the fuel control unit or
fuel system. The decision to attempt an engine restart during flight is
the pilot's responsibility and is dependent upon the pilot's experience
and the operating altitude. Consideration must be given to the cause of
the failure prior to attempting restart. Engine Restart [NATOPS
14.5] included
below.
-
Vibration identification - It is important to note that
sources of vibrations can only be from rotating or moving parts.
- Low frequency vibrations - Classified as one or two beats per
revolution. Most commonly caused by the main rotor. Vertical "One per" is
caused by an out-of-track condition, which causes more lift on one blade
than another at the same point of rotation. Lateral "One per" vibrations
are caused by a difference in weights of blades (spanwise imbalance)
or a misalignment of blades (chordwise imbalance). Two-to one vibrations
are inherent in two-blades systems at about 100 to 110 kts.
- Medium frequency vibrations - Classified as 4 to 6 beats per
revolution, they are also inherent in helicopters. If there is an increase,
it may be because of a change in aircraft's ability to absorb noise,
or a loose part vibrating with rotor system.
- High frequency vibrations - Felt as a "buzz" due to high speed.
Always present as well, it is caused by anything that vibrates at a speed
higher than that of the tail rotor. Common problems are tail rotor out-of-track,
out-of-balance, or worn tail rotor components. [NATOPS
11-9, AERO 5-12]
- Mast bumping - The result of excessive rotor flapping.
If flapping exceeds the maximum allowed angle, a static stop will violently
contact the mast, causing mast
damage or separation.
The most influential causes:
1) Low G maneuvers (below 0.5 g's)
2) Rapid, large cyclic movements (especially forward)
3) Flight near longitudinal / lateral CG limits
4) High slope landings.
Less influential causes:
1) Max sideward/rearward flight
2) Sideslip
3) Blade stall conditions
Warning • Should
mast bumping occur in flight, catastrophic results are probable.
Since conditions causing rotor flapping are cumulative, improper
pilot response/recovery techniques to flight situation approaching
or favorable to mast bumping can aggravate the situation and lead
to in-flight mast bumping and mast separation. [NATOPS
11.5]
Low
G flight, such as crossing a ridgeline, masking and unmasking,
acquiring/staying on a target, and recovery from a pull-up, allows
thrust to be unloaded from the rotor head. Incorrect pilot inputs
for
engine failure and tail rotor failure can also lead to excessive
flapping. Recover should be made by reapplying thrust to the rotor
head again,
usually through aft cyclic. [System
5-11]
MAST BUMPING [NATOPS 14.11]
Indications: Sharp two-rev knocking
During high speed sideward or rearward flight:
1. Cyclic - Immediately Apply Smoothly Toward CENTER
2. Pedals - Immediately Apply as Req. to Align the Nose with the Direction
of Travel
3. Land immediately
During other flight conditions:
1. Cyclic - Immediately Apply AFT to Establish Positive G Load
on Rotor, Then Center Laterally
2. Controls - As Required to Regain Balanced Flight
3. Land immediately
CONDITION
|
RECOVERY TECHNIQUE [NATOPS
11.6] |
Start/Shutdown:
|
Cyclic: Move to stop bumping |
Rear/Side flight:
|
Cyclic: Move slightly toward
center
Pedal: Align nose w/ direction of travel |
Slope Landing:
|
Cyclic: Move toward center
to stop bumping; reestablish hover |
Engine failure,
high forward airspeed
|
Cyclic: Move aft to maintain
positive G (positive thrust), retain Nr, and avoid mast
bumping during auto entry
Collective: As req. to maintain Nr |
Low G maneuvers
< 0.5G
(Other than nose high)
|
Cyclic: Aft, then center
laterally to regain positive g (positive thrust) on rotor
and maintain
Nr
Collective: Judiciously increase, if possible
Pedal: As req. |
Nose high,
low airspeed
|
Cyclic: Neutral |
- Ditching
- DITCHING - POWER ON [NATOPS
16.3.4.1]
Once the decision has been to made to ditch:
1. Passengers and crew - Alert
2. Shoulder harness - Locked
3. Mayday/IFF - Transmit/EMER
4. Perform a normal approach to 3 to 5 feet hover
5. Doors - Jettison
6. Nonessential personnel - Execute Emergency Egress
7. Helicopter - Move, Safe Distance Away
8. Vertical landing - Perform
9. Twist grip - Close
10. Collective - Increase Slowly to Maximum Pitch
11. Cyclic - Maintain Helicopter Upright As Long As Possible
12. Emergency Egress - Execute
13. Lifevest - Inflate (when well clear of helicopter)
- DITCHING - POWER OFF [NATOPS 16.3.4.2]
Time permitting:
1. Autorotate
2. Shoulder harness - Locked
If time and altitude permits:
3. Crew/passengers - Alert
4. Mayday - Transmit On Guard
5. Squawk - EMER
6. Doors - Jettison
WARNING • Do
not abandon helicopter until rotor blades have stopped. Do not
inflate lifevest until
well clear of the helo.
7. Underwater egress - Execute
.
(none for this event)
-
ENGINE OVERSPEED (Nf) ROTOR RPM (Nr) [NATOPS
14.6]
Indications:
increase in Nr,
Nf,
Ng,
TOT,
Right yaw,
Engine noise increase
1. Collective - Increase (to maintain Nr in operating range)
2. Twist grip - Reduce (to maintain Nf in operating
range)
3. Collective/twist grip - Readjust
4. Land as soon as possible
Note • The Nf overspeed must be continually
controlled by coordinating collective and twist grip.
- UNDERSPEEDING Nf/Nr [NATOPS
14.7]
Indications: Low Nr, Low Nf
If Nr can be maintained at 90% or higher in level flight,
it is safe to proceed to a suitable landing site. Terrain permitting,
a sliding landing offers the lowest power required. Do not decelerate
below the minimum airspeed of 50 KIAS while executing the power check.
If some usable power exists but level flight cannot be maintained, that
power, if sufficient, may be utilized to effect a landing or minimize
rate of descent en route to a more suitable site for autorotation.
1. Collective - Adjust to maintain Nr within limits
2. Twist grip - Full Open
3. GOV RPM - Full Increase
4. Check power available with Nr in limits
If power is not sufficient:
5. Autorotate
If sufficient power is available:
6. Land as soon as possible
- COMPRESSOR STALL [NATOPS
14.9]
Indications: Popping or rumbling noise, Vibrations, Rapid rise in TOT,
Ng fluctuation, Loss of power
1. Collective Reduce (maintain Nr within limits)
2. Reduce severity of maneuver
If TOT within limits:
3. Land as soon as possible
If TOT not within limits:
4. Twist grip Reduce to maintain TOT within limits
5. Check power available with Nr within limits
If power is not sufficient:
6. Autorotate
If sufficient power is available:
7. Land as soon as possible
WARNING
• Be prepared for a complete power loss.
• When accelerating the rotor system during the initial rotor
engagement or after a full autorotation, exceeding 40% torque may induce compressor
stall or engine chugging.
Note
• Slight power (collective) reduction will often eliminate
compressor stalls.
• Mild compressor stalls may occur that will allow powered
flight if TOT is within limits.
- ENGINE FAILURE [Adapted
NATOPS 14.1]
Indications: Nr decrease, Rapid settling, Left yaw, Low rotor rpm
caution light and audio, Engine-out caution light and audio
Immediately upon engine failure, rotor rpm will decay and the nose
will swing to the left, because of loss of power and torque. Except
when near surface, it is mandatory that autorotation be established
by immediately lowering the collective pitch to minimum. Right pedal
decreases tail rotor thrust. High gross weights, increased g loads,
and higher altitudes and temperatures will cause increased rpm, which
other than that specified for maximum glide {94-95%}, will cause
increased rates of descent. At 75 to 100 feet, a cyclic flare should
be established to reduce airspeed, rate of descent, and increase
rotor rpm. Caution should exercised to avoid striking tail; level
skids before ground contact.
Note
• The best glide airspeed is 72 KIAS. The minimum
rate of descent airspeed is 50 KIAS. Do not exceed 100 KIAS in sustained
autorotation.
• If time and altitude permit,
engine restart may be attempted. The decision to attempt a restart is the
pilot's responsibility and is dependent upon the pilot's experience and
operating attitude.
• All autorotative landings
should be made into the wind at a suitable landing site.
- ENGINE FAILURE AT HIGH AIRSPEED AND LOW ALTITUDE [NATOPS
14.1.1]
Should an engine failure occur at high airspeed and low altitude, a rapid
loss of Nr accompanied by a severe nose-tucking tendency will occur.
1. Cyclic Immediately Apply Aft
2. Autorotate
WARNING • Rapid
cyclic movement should be avoided to preclude mast bumping.
- ENGINE FAILURE IN FLIGHT [NATOPS
14.1.2]
In the event of an engine failure in flight, a safe landing can be accomplished,
provided that altitude and airspeed combination is within safe limits and
altitude is sufficient to permit selection of a suitable landing area.
1. Autorotate
2. Shoulder harness Locked
If time and altitude permit:
3. Crew/passengers Alert
4. Mayday Transmit on Guard
5. Squawk EMER
-
ENGINE RESTART IN FLIGHT [NATOPS
14.5]
An engine restart in flight would most likely result from a malfunction of
the fuel control unit or fuel system. The decision to attempt an engine restart
during flight is the pilot's responsibility and is dependent upon the pilot's
experience and the operating altitude. Consideration must be given to the cause
of the failure prior to attempting restart.
If attempting a restart, proceed as follows:
1. Autorotate
2. Fuel valve Check On
3. Starter Engage
If light off occurs:
4. Land as soon as possible
Caution
• If Ng is allowed to fall
below a minimum of 15% Ng the close the twist grip and perform a normal start.
• Do not attempt to start
above 12,000 feet as TOT rises too fast to control.
Note • Ng will not decrease
below minimum starting speed within 10 seconds because of rotational inertia
plus possible ram effect. The twist grip can be left in the full open position
since fuel flow during the start will be on the normal acceleration schedule.
-
ELECTRICAL FIRE [NATOPS
4.16]
Indications: Loadmeter/DC Voltmeter show excessive load,
Smoke, Fumes, SparksPrior to shutting off all electrical power, the pilot must consider the
equipment that is essential to the particular flight environment that will
be encountered (e.g., flight instruments and fuel boost pumps).
ELECTRICAL FIRE UNKNOWN ORIGIN [NATOPS
14.16.1]
1. BAT switch OFF
© 2. STANDBY GEN switch OFF
© 3. STBY ATT ID switch OFF if in VFR Conditions
4. MAIN GEN switch OFF
If fire persists:
5. Land immediately
If fire extinguishes:
6. Land as soon as possible
If the electrical power is required to restore minimum required equipment
for continued flight, proceed as follows:
7. All circuit breakers Out
© 8. Check BAT RELAY CB In
9. BAT switch ON
10. MAIN GEN FIELD and MAIN GEN CB In
11. MAIN GEN switch Reset, then ON
©12. STBY GEN switch ON
©13. STBY IND ATT switch ON
14. Circuit breakers for essential equipment In One at a Time in Order of Importance
Note
• Ensure corresponding bus supply circuit breakers are
in to provide power to desired electrical equipment.
• Voltmeter will not indicate
battery voltage until battery bus supply and voltmeter circuit breakers are
in.
• Flight operation can be maintained
without battery and generator. Instruments powered by the 28V DC power system,
however, will be inoperable.
ELECTRICAL FIRE KNOWN ORIGIN [NATOPS
14.16.2]
1. Affected equipment Secure
2. Affected C/B's Pull
If fire persists:
3. Electrical Fire Unknown Origin Proc. Execute
If fire extinguishes:
4. Land as soon as practicable {Because cause of fire known and extinguished}
-
MAIN DRIVE SHAFT FAILURE (BARBELL SHAFT FAILURE) [NATOPS
14.2]
Indications: Nr decrease, Nf/Ng rpm increase, Left yaw, Loud bang/noise
1. Autorotate
2. Twist grip Adjust to maintain Nf/Ng in operating range
When on deck:
3. Emergency shutdown Complete
WARNING
• The engine must continue to operate
to provide tail rotor drive. Tail rotor drive effectiveness may be lost if Nf
is allowed to go below 80%.
- All FAM stage checklists and voice reports - PRESTART
CHECKLISTS
- Normal starting/shutdown procedures - PRESTART
CHECKLISTS
- Abnormal starts - same as from CPT1
- Generator/electrical malfunctions - same as from CPT3
- Hydraulic system failure - same as from CPT3
- Chip light - same as from CPT3
- Post shutdown fire/internal - same as from CPT1
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