1. Discuss:
a. Loss of useful power (either a rollback or compressor stall):
Engine malfunctions may result in a loss of useful power where the power available is insufficient to prevent the high rates of descent associated with low power/low propeller blade pitch situations. To determine whether or not the propeller should be feathered, check the VSI while descending at 100 KIAS clean. A descent rate in excess of 600-800 fpm will require the propeller to be feathered. The best glide performance power setting at 100 KIAS, aircraft clean, is 205 ft-lbs.
ROLLBACK:
Reduced fuel flow (rollback)
is typical of a fuel control unit pneumatic sensing system malfunction.
If engine will not respond to PCL movements and ITT and N1 indicate the
engine is running at a very low power setting, advance the EPL in an attempt
to regain control of engine power by use of the manual fuel control system.
If N1 and ITT indicate that
a rollback condition exists (FCU stuck at minimum flow), proceed as follows:
1) Condition lever
- FULL INCREASE RPM
2) EPL - ADVANCE TO DESIRED POWER SETTING
If sufficient power is restored:
3) PCL - IDLE
4) PEL - EXECUTE
CAUTION - Use of beta is not recommended when performing a landing using the manual fuel control system. If the use of beta is required, ensure the EPL is in the IDLE range or DISCONNECT before selecting BETA with the PCL.
If the resultant power is
insufficient to execute a PEL:
5) EPL - DISCONNECT
6) Proceed to the nearest suitable landing field and execute the ENGINE FAILURE procedure.
WARNING - When the engine is so underpowered that high rates of descent occur, any delay in feathering the propeller may result in insufficient altitude to reach a suitable landing site.
NOTE - If resultant power is sufficient to maintain a rate of descent less than the feathered condition (600-800 fpm clean), consideration should be given to allowing the engine to operate until the field is made.
If the application of power
results in compressor stall indications (possible compressor bleed valve
malfunction), execute the COMPRESSOR STALLS procedure.
COMPRESSOR STALL:
Compressor stalls may be characterized by an audible change in engine noise (a loud bang or backfire) with fluctuations in torque, ITT, N1, and fuel flow. Additionally, flames and smoke may be visible from the engine exhaust stacks. A severe compressor stall may result in engine damage and/or flameout. Compressor stalls may be caused by damaged or degraded compressor or turbine blades, disrupted airflow, or compressor bleed valve malfunction.
If compressor stalls occur,
proceed as follows:
1) PCL - SLOWLY RETARD
TO JUST BELOW STALL THRESHOLD TO CLEAR STALL
2) Cockpit environmental control - FULL FORWARD
3) PCL - SLOWLY ADJUST TO DESIRED POWER SETTING
WARNING - Avoid unnecessary PCL movement. Advancing the PCL may result in further compressor stalls and engine flameout. Retarding the PCL further may limit maximum power available.
If sufficient power is available:
4) PEL - EXECUTE
If sufficient power is insufficient
to execute a PEL:
5) Proceed to the
nearest suitable landing field and execute the
ENGINE FAILURE procedure.
WARNING - Use of manual fuel control will only aggravate compressor stalls and could lead to flameout.
WARNING - When the engine is so underpowered that high rates of descent occur, any delay in feathering the propeller may result in insufficient altitude to reach a suitable landing site.
NOTE - If the situation permits, record the altimeter, OAT, max ITT, and duration of compressor stall.
NOTE - If resultant power is sufficient to maintain a rate of descent less than the feathered condition (600-800 fpm clean), consideration should be given to allowing the engine to operate until the field is made.
b. Use of emergency power lever (EPL)
The manual fuel control system
consists of a cockpit control which provides the pilot with direct mechanical
linkage to the bellows and the fuel metering pin in the FCU. The
manual fuel system is a backup system only and is used in the event of
a malfunction in the pneumatic section of the FCU.
When engaged, the system
will bypass all pneumatic failure modes which result in minimum fuel flow
and/or lack of engine response to PCL movement. Movement of the emergency
power lever (EPL) toward max, mechanically depresses the bellows to schedule
more fuel to the engine. This system relies on torque tube pretension
to reduce power as the EPL is moved toward the idle range. When using
the EPL, normal operation of the landing gear warning system is provided.
If loss of power occurs
due to a malfunction of the FCU, power may be restored using the EPL.
No automatic fuel scheduling is incorporated, and fuel metered to the engine
is a direct function of the lever position. Idle RPM, when required, should
be maintained above 65% N1 by the pilot to eliminate the lack of EPL response
in the idle range, and improve engine response. The manual fuel control
system bypasses the protective devices relying on pneumatic bleed air as
the operational parameter for the fuel topping function of the primary
governor. Failure of the FCU at high power cannot be corrected with
the EPL.
NOTE - With gear up, normal operation of the gear warning system occurs when the PCL and the EPL are retarded below 75% N1. Additionally, the warning system will activate (with gear up) when both the PCL and EPL are forward of the 75% switch.
CAUTION - Compressor stall, vibrations and overtemp are probable with rapid accelerations of the EPL, particularly at the low-end of the power spectrum.
CAUTION - During an actual rollback, if power is restored with the EPL, exercise caution not to excessively reduce power in the final landing transition, as sink rate will drastically increase at low power.
Procedures:
1) EPL activation:
a) Condition lever - FULL INCREASE
b) EPL - Out of detent; slowly advance to desired power setting.
c) PCL - IDLE
2) EPL Normal Use - Utilize smoothly in the same manner as the PCL with considerations/limitations as set forth above. The use of the EPL will only be practiced at altitude. It will NOT be used for training purposes in either the normal or emergency landing patterns.
3) EPL deactivation:
a) PCL - advance to power setting above EPL
b) EPL - DISCONNECT
Common errors:
1) Failure to check
condition lever at full increase.
2) Failure to operate
the EPL smoothly on activation.
3) Failure to monitor
power settings during changes in altitude.
4) Using the PCL for
operation of the manual fuel system after EPL is
engaged.
c. Propeller failures
Normally, the primary and
overspeed governor and fuel topping function will act in sequence to hold
propeller rpm within suitable range to continue flight or to reach a suitable
repair facility. If the propeller is being governed by the fuel topping
governor alone, expect moderate surges in propeller rpm, N1, torque and
fuel flow as fuel topping activates and deactivates. Depending upon
the type of failure, proceed as follows:
Propeller RPM 2200-2332 RPM
(Primary Governor Failure):
1) Attempt to adjust
rpm to normal operating range by manipulation of the condition lever.
If normal indication is restored, continue flight.
2) If adjustment of the condition lever fails to produce normal propeller response, land as soon as possible utilizing PEL procedures.
Propeller RPM above 2332
RPM (Overspeed Governor Failure):
1) Attempt to adjust
rpm to normal operating range by manipulation of the condition lever.
If normal indication is restored, land as soon as practical using normal
procedures.
2) If adjustment of the condition lever fails to produce normal propeller response, land as soon as possible utilizing PEL procedures.
CAUTION - Advancing the EPL beyond the point at which the fluctuations are minimized will aggravate the overspeed condition.
NOTE - If activation of the primary fuel topping governor has occurred, Py air will be bled automatically and fuel flow will be reduced towards minimum, causing corresponding fluctuations in N1, torque, fuel flow, and prop rpm as rpm surges to 2398 and is then reduced again by the fuel topping function. Engaging the EPL will lessen the severity of low-end fluctuations.
Propeller feathers:
1) Condition lever
- FULL INCREASE RPM
If propeller remains feathered:
2) PCL - ADVANCE (as
required)
NOTE - In the event of a primary governor shaft failure, the propeller will move toward feather; however, unboosted engine oil pressure alone may be sufficient to maintain propeller pitch between feather and normal governing rpm range at high-power settings. Resultant power may be sufficient to maintain level flight.
If the resultant power does
not improve performance:
3) PCL - IDLE
4) Execute ENGINE FAILURE procedures.
NOTE - Because it is feasible for the propeller to unfeather and restore useful power, consideration should be given to leaving the condition lever at FULL INCREASE RPM until intercepting the emergency landing pattern (ELP).
NOTE - Generator power will not be available after engine shutdown.
Propeller RPM fluctuations:
Propeller rpm fluctuations
caused by fluctuating blade angle will be accompanied by a corresponding
torque flux and will be audible. Propeller rpm fluctuations may be
caused by a faulty propeller overspeed governor test circuit or a malfunctioning
primary governor. A malfunctioning primary governor may be caused
by metal particles in the oil system and may therefore be the precursor
to a chip light. Proceed as follows:
1) PROP TEST circuit
breaker - PULL
If fluctuations cease, continue
flight. If fluctuations continue:
2) Land as soon as
possible using PEL procedures.
2. Demonstrate:
a. Use of the EPL
3. Introduce:
a. Use of the EPL
b. PPEL from the pattern (PPEL(P))
c. LAPL from the pattern (LAPL(P))
4. Practice:
a. ATS
b. Spin
c. HAPL
d. LAPL
e. PPEL
f. Landing pattern
g. Full flap landings
h. No flap landings
i. Waveoff
5. Non-graded:
a. Ground procedures
b. Takeoff/departure
c. TP
d. OFO
e. Aborted takeoff
6. Review:
a. Course rules/COMM/IFF/HFE