Three Eagle 150 aircraft, VH-EAD, VH-FPO and VH-JBA, were
engaged on a training flight for an airshow formation routine. The
lead aircraft, EAD, was callsign Eagle 1; FPO was Eagle 2 and JBA
was Eagle 3. They were operating at heights between 500 ft and 800
ft. Eagle 2 carried a passenger who was a former Royal Air Force
pilot with extensive formation flying experience. The other
aircraft did not carry passengers.
The training sequence usually included a formation flypast at
500 ft, followed by a break into a bomb-burst manoeuvre. Following
the bomb burst, Eagle 1 would pull up steeply to about 800 ft for
some low-speed manoeuvres with flaps extended. Eagles 2 and 3 would
remain at 500 ft and complete a pass close to each other as they
flew in opposite directions. The aircraft would then rejoin for a
formation flypast, followed by a break for a stream landing.
On the day of the accident, the pilots practised their routine
(except the stream landing) four times. Then, after the bomb burst
during the fifth practice, Eagle 1 climbed to between 700 ft and
800 ft for the low-speed manoeuvres with flaps extended, while
Eagles 2 and 3 performed their close pass in opposite directions.
As the three aircraft were manoeuvring for a rejoin, the passenger
in Eagle 2 observed Eagle 1 roll to the right, flick inverted, and
begin rotating to the right in a steep nose-down attitude. The
rotation stopped after about one revolution, but the aircraft
flicked a second time. The rotation ceased again after about one
revolution, but the aircraft flicked inverted again. The pilot did
not effect recovery before the aircraft impacted the ground.
Examination of the wreckage did not reveal any defect that may
have contributed to the accident. Measurement of a flap actuator
extension indicated that the wing flaps were extended to 32 degrees
(91% of the maximum extension available ) at the time of impact.
The elevator trim tab was set to 18 degrees up, indicating that the
aircraft was trimmed for level flight at 61 kts indicated airspeed
with the flaps set to 35 degrees.
The weather conditions at the time of the accident were fine,
with a slight sea breeze from the south-east at 2 to 3 kts, with a
surface temperature of 13 degrees C, visibility of more than 15 km
and no low cloud.
The pilot of Eagle 1 held a Private Pilot Licence with a current
Class 2 medical certificate. He had accumulated a total of about
780 flying hours including 47 hours on Eagle aircraft, which he had
been flying for about 22 months. About 39 hours of his Eagle
experience had been gained on X-TS 150 aircraft and about 8 hours
on EAD, a 150 B variant. The X-TS 150 variant is powered by a
Continental IO-240A engine driving a McCauley 70-inch diameter
propeller of 54-inch fixed pitch, whereas the 150 B variant is
powered by a Continental IO-240B engine driving a McCauley 70-inch
diameter propeller of 57-inch fixed pitch. There are physical
differences between the engines but power outputs are the same. The
main difference between the variants was the propeller pitch.
Consequently, the performance of the 150B variant, having a
propeller with a cruise pitch, would be slower to respond to a
rapid increase in power than the X-TS 150.
The pilot had completed a formation flying endorsement
approximately 3.5 years previously. Since 26 January 1997 he had
accumulated about 47 hours of formation flying in Eagle, Piper
Cherokee and Cessna 150 aircraft. He did not hold an aerobatic
rating. The pilot's last Biennial Flight Review was completed on 22
November 1998 in an Eagle X-TS 150 aircraft. His last flight before
the accident flight had been in EAD 4 days before the accident. The
pilot's last airshow routine practice was at Avalon on 16 May
1999.
No pre-existing medical or toxological condition that may have
contributed to the accident was identified during the pilot's
autopsy.
The Eagle 150 B aircraft was granted Certificate of Type
Approval 179-1 by the Civil Aviation Safety Authority (CASA), on 11
November 1997. The process of certification included extensive
testing of the aircraft in accordance with Joint Aviation
Requirements-Very Light Aeroplanes (JAR-VLA).
The stall characteristics of the Eagle were tested in accordance
with JAR - VLA 201, 203, 207 and 221. The flight-test program
included stalling the aircraft in more than 200 different
combinations of configuration, airspeed, deceleration rate,
attitude, flight path and G loading. The aircraft met or exceeded
the requirements of JAR-VLA, demonstrating generally benign stall
characteristics in all configurations when in balanced flight at
the point of stall. Entry into a stall from unbalanced flight could
result in an incipient spin.
If a pilot releases pressure on the flight controls after
entering an incipient spin, the aircraft should cease rotating and
assume a steep nose-down attitude. The pilot can then recover the
aircraft to level flight. If the pilot immediately begins spin
recovery actions as described in the "Pilot's Operating Handbook
and Approved Flight Manual" for the Eagle 150 B, the aircraft
should be capable of recovery to level flight from a single-turn
incipient spin.
In production test flying, EAD had demonstrated normal stall
characteristics.
The Flight Manual, Section 3.7 stated in part:
"Intentional spins are prohibited in this aircraft. Should an
inadvertent spin occur, the following recovery procedure should be
used:
- Retard the throttle to idle
- Centralise controls
- Retract flaps
If the aircraft continues to spin:
- Determine the direction of rotation by visual method or by
reference to the turn indicator (turn and balance indicator) - Apply and hold full rudder opposite to the direction of
rotation - If the aircraft fails to stop rotating, move control column
smoothly forward until rotation stops - As rotation stops, centralise controls, roll wings level and
pull the aircraft out of the dive".
The section included the following note:
"Rotation may seem to increase in speed when forward controls
are applied, this is normal and is to be expected just prior to
rotation stopping". In this occurrence, the aircraft was observed
to roll steeply to the right and then enter a steep nose-down
attitude consistent with a stall followed by an incipient spin.
Immediately before this, the aircraft was manoeuvring at low
airspeed, with flaps extended. The pilot did not retract the flaps
in accordance with the aircraft Flight Manual's spin-recovery
procedure, but certification test flying had shown that this should
not have affected the aircraft's capability to recover.
The pilot had considerably more experience on the X-TS 150
variant than on the 150 B variant, but it is unlikely that
differences between the two variants affected the circumstances of
the accident.
At the time of the stall, the aircraft was turning right at low
airspeed. The passenger in Eagle 2 was giving advice to the pilot
of Eagle 1 concerning manoeuvres to enable Eagles 2 and 3 to rejoin
formation more efficiently. It is possible the pilot of Eagle 1 was
focussing on the rejoin manoeuvre to the extent that he did not
recognise the onset of the stall.
The observed manoeuvres are consistent with a stall from an
uncoordinated right turn, followed by an incipient spin from which
recovery was not effected. The reason the pilot was unable to
recover the aircraft from the spin could not be determined.