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gear is being retracted, note if there is any tendency
for the aircraft to yaw, pitch, or roll. Record what
changes to the aircraft’s trim are required to maintain
straight and level flight. If there are no adverse flight
reactions or system malfunctions, cycle the gear several
times. When satisfied with the straight and level
gear retraction test, try an emergency gear extension
but only if this is practical.
c. With the gear extended, slow the aircraft
to 1.3 times the pre-determined stall speed, stabilize,
lower the flaps to the take-off position, trim, and
maintain straight and level flight.
d. Simulate a normal takeoff by increasing
rpm to full power. Raise the nose 3 degrees, trim,
and then retract the gear. Observe the following: aircraft
reaction, such as pitch or roll; length of time
for gear to retract; trim requirements;, and the time
necessary to establish a 1,000-foot climb before
leveling off.
e. Practice a simulated takeoff several times
to ensure that the aircraft’s response is predictable
and the gear retraction system is mechanically reliable.
4. CLIMBS AND DESCENTS. The purpose of
these tests is to monitor engine performance and
reliability. The pilot should start the test only after
the aircraft has been flying straight and level for a
minimum of 10 minutes to stabilize engine oil pressure
and temperatures.
a. Engine oil pressure and temperatures must
be kept within the manufacturer’s limits at all times
during these tests. High summer temperatures may
place restrictions on the flight test program because
both oil and cylinder head temperatures will increase
1 degree for each 1 degree increase in outside
temperature.
(1) Climbs. Start the first climb at a 15
degree climb angle, full power, at a predetermined
designated altitude (e.g., 1,000 feet). Maintain the
climb angle for 1 minute. Record the engine temperatures
and pressures. Reduce power, stabilize the
engine temperature, and repeat the test. For the second
climb test, the Flight Test Plan should call for
increasing the climb time -- record the results. When
satisfied that an engine cooling problem does not
exist at this climb angle, repeat the tests using steeper
climb angles until the pilot has reached 15 degrees
or encountered an engine manufacturer’s limit or a
5-minute climb period at full throttle has been
reached.
(2) Descents. Should begin above 5,000
feet AGL with both the engine temperatures and
pressures stabilized.
(i) The test pilot should use carb
heat and clear the airspace below him before
starting the descent. The first descent should be
at a shallow angle, at low rpm and last for 30 seconds,
not exceeding 1.5 times the estimated stall
speed of the aircraft. During long, low power
descents, the pilot must be on the alert for too rapid
cooling of the engine usually identified by a signifi43
5/24/95 AC 90-89A
cant drop in oil and CHT temperature. If a noticeable
drop occurs, increase the engine rpm and reduce the
angle of descent. If not corrected, the repeated rapid
cooling of the engine may cause thermal shock to
the engine cylinders and eventually cause cylinder
head cracking or seizure.
(ii) Conduct each test as before, but
increase the time by 30 seconds until limited by the
engine manufacturer’s restrictions or 5-minute
descents are reached. Record temperatures, pressures,
altitudes, and airspeeds data for climbs and
descents for addition into the aircraft’s flight manual.
5. AIRSPEED IN-FLIGHT ACCURACY
CHECK. The following procedure for airspeed
calibration is offered for evaluation:
a. A measured course should be chosen with
readily identifiable landmarks at each end. The landmarks
should be a known distance apart, and the
length of course should be at least 1 to 2 miles long.
b. The pilot must fly a precision course
maintaining a constant altitude (e.g., 1,000 feet), constant
airspeed, constant magnetic heading, and constant
engine rpm. The pilot must record the temperature,
altitude, indicated airspeed and the time over
each landmark for both directions. The average of
these speeds is the ground speed of the aircraft. An
E6B computer will convert the temperature, altitude,
and ground speed into True Indicated Airspeed for
the tests.
NOTE: The difference between the E6B
computer readings and the aircraft’s ground
speed readings is the error in the instrument
and the error caused by the installation of
the system in the aircraft.
c. The airspeed calibrations runs should be
　
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