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(5) Notice any changes in flight characteristics
and the speeds at which they take place. Be
especially alert for the onset of pre-stall buffet. Is
the buffet felt through the stick? Through the airframe?
Though the seat of the pants? Does the nose
of the airplane want to rise or drop on its own? How
strong is the buffet? Is it continuous? Would it get
the pilot’s attention if they were concentrating on
something else?
NOTE: On some high performance aircraft
and aircraft with unusual wing designs, a
pre-stall buffet may not exist and the stall
may be abrupt and violent with a large
degree of wing drop.
(6) Keep making small control inputs at
intervals to check the aircraft’s responses. At
approximately 5 mph/knots before the predicted stall
speed, or at the first sign of a pre-stall buffet, note
the airspeed and stop the test. Recover and write
down the pre-stall indicated airspeed. This airspeed
should be the reference stall speed for the first landing.
(7) The pre-stall recovery response should
be a smooth and quick forward stick movement. This
response should be enough to reduce the angle of
attack to the point where the airplane is flying normally
again.
(8) A wing drop would be unexpected so
early in the approach to a stall, but if it becomes
necessary to raise a low wing do it with rudder, NOT
OPPOSITE AILERON. Use of ailerons at lower
speed would increase the chances for a stall or a
sudden departure from controlled flight.
(9) There is no need to gain more airspeed
than the extra few mph/knots to fly out of a prestall
condition. After returning to straight and level
flight and using the information learned, the pilot
can practice a few more recoveries from a pre-stall
condition. Remember the aircraft will constantly be
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loosing altitude so it is necessary to climb back up
to 5,000 feet AGL to continue further flight testing.
Do not get so involved that the overall objective of
the first flight is lost -- which is getting the pilot
and aircraft safely back on the ground.
(10) The FLIGHT TEST PLAN for the first
flight should call for a maximum of 1 hour of actual
flight time. This is to reduce pilot fatigue and the
possibility of an engine failure or airframe malfunction
occurring due to vibration or construction errors.
NOTE: The pilot may elect to make several
practice approaches to landing at altitude or
low approaches to the active runway to get
a solid understanding of the lower airspeeds,
aircraft attitude, and overall feel of the aircraft
in the landing configuration. Before
each low approach at the airport, the tower/
UNICOM/chase plane should be advised of
the pilot’s intentions. Avoid other traffic in
the pattern, and use the landing checklist.
(11) When the pilot has completed all the
tests called for by the FLIGHT TEST PLAN, notify
the tower/UNICOM/chase plane of the intent to land.
Complete the landing checklist before entering
downwind. Keep all turns less than 20 degrees of
bank, but do not cross-control by using the rudder
to move the nose. This will increase the bank angle,
which most pilots will correct by using opposite aileron.
If allowed to continue, and with back pressure
on the stick, this will result in a cross-control stall
and a roll to a near vertical bank attitude at the beginning
of a spin with no altitude left for recovery.
(12) On final approach, the aircraft speed
should be no less than 1.3 but no more than 1.4
times the recorded ‘‘first flight’’ pre-stall speed.
Homebuilt biplanes (high drag) should use an
approach speed of 1.5 x stall speed on landings.
(13) Landings, especially the first one in an
amateur-built or kit plane, are always exciting. Proceed
slowly and do not over control. If the landing
conditions are not ideal, be prepared to go around.
(14) The actual touchdown should take
place within the first 1,000 feet with braking action
being applied before the red (abort) flag marker on
the runway.
(15) After taxiing in, secure the aircraft,
debrief the flight with members of the team, then
together perform a careful post-flight inspection of
the aircraft.
NOTE: Remember to allow enough time to
absorb what has been learned about the aircraft’s
performance and the pilot’s and
ground crew’s responses to it.
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5/24/95 AC 90-89A
CHAPTER 4. THE FIRST 10 HOURS
‘‘One can get a proper insight into the practice of flying only by actual flying experiments.’’
　
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