The interesting aspect in the post from John is the conclusion.

 

“It appears to me as a non-aero dynamist, a non-engineer, but a keenly interested follower of the tragedies that are befalling our community, that this aircraft cannot be flown slow, cannot be inadvertently flown close to its stall and must be built with great care and an even higher level of precision.”

 

Wise observation.

I wonder though, at the end of the day, if the resultant cause of these and the two most recent accidents in Australia is the natural tendency to either deliberately or otherwise allow the nose to pitch up with loss of power , when close to the ground, with the established catastrophic results. Trying to turn back from low level has the same effect.

The Geelong accident on 20 Dec 2002 had other factors involved.

I suggest there is a lesson to learnt here with determining stall points.

I didn’t fly the DC9, preferring a much more engined life, but if my ageing memory is even close, I understand it had a pusher installed to prevent deep stalling of the wing after testing demonstrated that in a deep stall the horizontal stab. was blanketed by the wing.

I wonder if non-test qualified pilots without proper equipment should be involved in stall tests to the point of extended stall conditions in the Lancair?

While most pilots have no qualms about placing a Cessna or Piper into a full stall, I choose not to do so with my Lancair. My aircraft gives a wide margin audio warning, and develops a sink which sustains unless full backstick is applied., then settles into an increasing sink rate, wings level. At this point I release back pressure and institute recovery, but the height loss can be significant throughout if backstick is not applied early.

An approach configuration approach to stall with power (say 20” MAP) has a torque induced yaw which is sort of comfortable to about 58 knots and that’s it.

I admit I am very conservative and prefer to operate well within the envelope, with pre-planned self briefed mindset of procedures if failure occurs during the critical phases.

This is standard airline type stuff with the exception if one quits there is no noise.

The two LNC2 accidents referred to above had almost identical last phase events – vertical descent into the ground from low level after a turn had been observed from ground witnesses.

The second of the two had some hundreds of hours in Lancairs. The first limited total time, around 300 hours, and 29 hours in his Lancair.

The Geelong accident report stated that the Lancair IV involved became laterally unstable below 80 knots in tests.

For some reason, there were two POB despite the test program being designed for single pilot operations.

From the report: “During the flight when the accident occurred, the aircraft departed controlled flight from a deliberately induced stall during a test flight. The aircraft then descended rapidly, at an airspeed that was not consistent with a stalled or spinning configuration. The aircraft instruments displayed a stall speed that was significantly below the actual stall speed in that configuration. It is possible that the stall occurred before the flight crew expected it.”

And: Documentation indicated that during construction, numerous changes had been made to the original design, including the engine type and the design of the aircraft from the firewall forward. The propeller had been modified by removing 20 cm of the propeller tips. No evidence was found to indicate that any form of risk assessment had been undertaken to consider the safety implication of these aircraft design changes. A risk assessment was not required for aircraft constructed under the experimental designation.

I think these are matters of interest for us.

Dom Crain