TM 1-1520-238-10
9-6
Change 9
and density altitude combinations that will permit a safe
landing in event of a single engine failure with average pi-
lot alertness, skill, and reaction time. The CAUTION re-
gion represents the airspeed and wheel–height combina-
tions in which constant pilot alertness and rapid reactions
are required in the event of a single engine failure to ac-
complish a safe single engine landing. The AVOID region
represents hazardous airspeed and wheel–height com-
binations from which a single engine landing would be ex-
tremely difficult without some degree of aircraft damage or
crewmember injury. Crewmember alertness, correct rec-
ognition and subsequent action are essential to perform a
successful single engine landing. Crewmember actions
should be based on the following general guidelines: 1) At
low density altitude and low airspeed, it may be necessary
to lower the collective only enough to maintain Nr in the
normal range, 2) At higher density altitudes, the collective
may be lowered significantly to increase Nr to normal lim-
its, 3) When hovering in ground effect, the collective
should be used only as required to cushion the landing,
and the primary consideration is in maintaining a level atti-
tude, 4) In forward flight at low altitude (as in takeoff or
landing) when single-engine capability to maintain altitude
does not exist, a decelerating attitude will initially be re-
quired to prepare for landing, 5) The height velocity dia-
gram is based on zero winds. If the aircraft is hovering in
a tailwind when an engine failure occurs, consideration
must be given to making a banking turn (preferable right)
and/or pedal turn (preferable right) to preclude accelerat-
ing the aircraft further into the AVOID region. If airspeed is
low and altitude above obstacles is sufficient, the helicop-
ter should be placed in an accelerating attitude to gain suf-
ficient airspeed for single-engine fly-away to a selected
landing site, and 6) When the power available during
single-engine operation will not support continued flight,
the crew should jettison external wing stores as an imme-
diate means of reducing power requirements and mini-
mum single–engine airspeed values.
9.5.3 Single Engine Failure Low Altitude/Low Air-
speed and Cruise.
1. Airspeed – Adjust as necessary.
If continued flight is NOT possible:
2. WING STORES JETTISON
If conditions still do not support continued flight:
3. LAND AS SOON AS POSSIBLE.
If continued flight is possible:
4. LAND AS SOON AS PRACTICABLE.
