9.36 EXTERNAL EXTENDED RANGE FUEL SYS-TEM FAILURE TO TRANSFER SYMMETRICALLY IN MANUAL MODE.
a.
Total failure of a single external extended range fuel system tank to transfer fuel could be the result of a loose .ller cap, bleed-air regulator/shutoff valve, fuel shutoff valve, or line blockage failure.
b.
Total failure of one tank to transfer fuel will turn on the associated tank’s NO FLOW light. Reduced .ow from one tank may not cause a NO FLOW light to go on, but will change the lateral CG of the helicopter. The pilot will notice a migration of the lateral cyclic stick position as the lateral CG offset from neutral increases. For example, a fully asymmetric outboard 230-gallon tank set (one tank full, one tank empty), on an otherwise neutrally balanced H-60, will result in a level .ight lateral stick position offset of approximately two inches. If asymmetric transfer is sus-pected, stop transfer on the selected tank set and initiate transfer on the other tank set, if installed.
If asymmetric fuel transfer is suspected:
1.
Stop transfer on tank set.
2.
Select other tank set and initiate transfer.
3.
LAND AS SOON AS PRACTICABLE.
With asymmetric fuel loading, lateral con-trol margin will be reduced in the direc-tion opposite the heavy side. The aircraft has been .own from hover to 138 KIAS, with lateral CG’s equivalent to a fully asymmetric outboard 230-gallon tank set, (full right tank, no stores on left side). The most critical maneuvers are turns toward the heavy side and approaches with a crosswind from the lighter side. These maneuvers are not recommended. The most adverse condition for lateral control-lability is right side heavy, in the 20 to 50 KIAS range. Do not exceed 30 degree angle of bank. If controllability is in ques-tion, jettison the asymmetric tank set.
Should controlled .ight with one heavy external tank become necessary, proceed as follows:
1.
Make all turns shallow (up to standard rate), and in the direction away from heavy side (par-ticularly when a right tank remains full).
2.
Avoid abrupt control motions, especially lateral cyclic.
3.
If possible, shift personnel to the light side of the helicopter.
4.
Select a suitable roll-on landing area, and make a roll-on landing with touchdown speed in ex-cess of 30 KIAS. To increase control margin, execute the approach into the wind or with a front quartering wind from the heavy side and align the longitudinal axis of the aircraft with the ground track upon commencing the approach. If a suitable roll-on landing area is not available, make an approach to a hover into the wind, or with a front quartering wind from the heavy side.
9.37 EXTERNAL STORES JETTISON.
ES
At high gross weights and with one engine inoperative, or in an emergency or performance limited situation, it may be necessary to jettison a tank set. Circuitry prevents the release of any individual tank even if a single tank jettison has been selected at the STORES JETTISON control panel. The helicopter will remain controllable even if a single tank fails to release because of a malfunction in the jettison system.
If jettisoning of tanks is required:
STORES JETTISON switch -Select OUTBD BOTH or ALL as applicable.
JETT switch -Actuate. If primary jettison system does not operate:
9-24
TM 1-1520-253-10
EMER JETT ALL switch -Actuate.
9.38 FUEL FUMES IN COCKPIT/CABIN WITH EX-TERNAL EXTENDED RANGE FUEL SYSTEM PRESSURIZED.
If the bleed air check valve(s) is stuck in the open posi-tion when the heater is turned on, the resulting bleed air manifold pressure drops due to the heater bleed air de-mands. This allows fumes/mist above the tanks to back.ow through the bleed air manifold, through the heater, and into the cabin. If fuel fumes or mist are noted during external extended range fuel system operation, perform the follow-ing:
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