Change 19 4-16.1
4-3. Power Loss, N2 Droop or Flameout Parameter
Maintenance Check Procedures. See applicable air-
craft Maintenance Test Flight Manual (MTF).
Check maintenance procedures for OH-58 aircraft
when a power loss, N2 droop, or flameout occurs. N2
droop may occur during a normal flight maneuver requir-
ing a rapid increase in power (i.e., rapid collective and or
tail rotor inputs, high G turn, steep turn). If N2 droop
occurs but low RPM warning is not activated and N2
recovers to 100 percent on OH-58C, and further N2
droop is not experienced, no maintenance action is re-
For all maintenance actions notes below,
pneumatic line fittings are to be torqued to
specified values utilizing a torque wrench. All
lines are to be installed so that there is no
preload or deformation of the in accordance
with applicable TM's.
When a power loss, N2 droop, or flameout occurs
(in parameters other than those established in paragraph
above), check/inspect to determine the reason/reasons
in accordance with the troubleshooting charts in table
If a reason/reasons for power degradation can-
not be established using the procedures specified in
paragraph above, request assistance from AVIM Mainte-
nance and proceed with the maintenance actions noted
in paragraphs (1) through (5) below. If this is a second
occurrence of power degradation on this aircraft/engine
and the maintenance actions listed below have been
complied within the last 100 flying hours, replace the
Check engine controls for proper rigging.
Check throttle angle on fuel control at idle detent for the
pilot's and co-pilot's twist grip. Maximum allowable varia-
tion between the pilot's and co-pilot's twist grip is
5/64-inch as measured on the fuel control sector. Re-rig
55-1520-228-23 and per this TM for OH-58C.
Remove engine fuel and pneumatic lines.
Replace engine fuel filter P/N 6895177, NSN
2915-01-040-2607 on OH-58C aircraft. Inspect fittings
and lines for cracks, scratches, dents and improper seat-
ing on sealing surfaces. If cracks in fittings or lines are
suspected, refer to TM 1-1520-254-23, Technical Manu-
al; Aviation Unit Maintenance (AVUM) Manual Nonde-
structive Inspection Procedure for OH-58 Helicopter Se-
ries. Inspect lines and fittings for contamination. Clean all
lines per applicable TM's. Inspect lines for chafing, check
compressor bleed valve. Correct any discrepancies. In-
spect and clean PC filter P/N 687458, NSN
2945-00-231-8065 (OH-58C only) On OH-58C replace
fuel nozzle P/N 6890917, NSN 2915-01-039-4730 and
check valve P/N 6895171, NSN 4820-01-045-0205. Re-
install pneumatic lines and filter. Leak check pneumatic
system in accordance with TM 55-2840-241-23. Check
compressor bleed valve for proper operation.
Remove all hoses, fittings and valve includ-
ing fuel shutoff valve from the fuel boost pump to the
engine. Clean and inspect all for damage and restric-
tions. Reinstall or replace as applicable. Bleed the fuel
system in accordance with the appropriate TM. With air-
craft fuel shutoff valve open, start boost pump and check
all accessible fuel lines, connections, and fittings outside
the fuel cell for leakage. Inspect and lubricate starter
generator splines. Check calibration of dual tachometer
(N2 and rotor RPM).
Check main and tail rotor systems for proper
rigging and pitch angle, and re-rig as necessary.
Start engine and perform deceleration
check. If deceleration check is not in limits, replace fuel
control P/N 6895672 NSN 2915-01-034-4671; N2 gover-
nor P/N 6895673, NSN 2915-01-034-4317 and double
check valve P/N 6876557, NSN 4820-01-047-2796 on
OH-58C aircraft. Repeat deceleration check, if satisfac-
tory, perform test flight in accordance with established
Aircraft are restricted from NOE contour, low lev-
el, and night flight for 10 hours after completion of the
preceding procedures and must be flown at an altitude to
55-1520-228-10. After completion of the 10-hour restric-
tion, repeat deceleration check. If satisfactory, perform
test flight in accordance with established procedures. No
further flight restrictions are imposed.
After completion of power loss, N2 droop, or
flame out, parameter maintenance check procedures,
make an entry on engine DA Form 2408-15 citing date
the inspection was performed and engine hours at the
time inspection was performed.
4-4. Engine Performance Check. See applicable air-
craft Maintenance Test Flight Manual (MTF).