Lancair crash near geelong Melbourne
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Homebuilt test flying hazards
Sussit has asked for info on a Lancair fatal near Melbourne, Australia. I am not a ETPS graduate so please understand that the following questions may be a bit amateur.
The Lancair concerned was a first of type unpressurised version with a Walther 700 SHP turbo-prop. Around three flights were carried out by non-test pilot qualified pilots - but experienced flying instructors. It is believed that the fatal flight was for purpose of stall checking at 4000 ft. Control was obviously lost with one witness stating that aircraft appeared to perform an aerobatic manoeuvre.
It was known that on previous flights that the engine idled at high rpm producing significant torque. The owner had also opted to change the engine centre line angle downwards by three degrees to solve a problem with fitting of the nose cowl. Also one of the pilots who first flew the aircraft reported a severe wing drop at the stall.
Questions: Would a high idle rpm contribute towards a severe wing drop?
With this type of engine, would a significant power application as would normally be applied in a stall recovery, cause a torque roll at low IAS?
Would there be a significant gyroscopic effect if rapid power was introduced as part of a stall recovery - and the nose lowered harshly?
What effect would a three degree lowering of the engine centre line have on aircraft handling near the stall?
The wreckage pattern seems to indicate high angle of descent in a flat attitude. This observation is purely from a media picture of the scene and may well be misleading.
The Lancair concerned was a first of type unpressurised version with a Walther 700 SHP turbo-prop. Around three flights were carried out by non-test pilot qualified pilots - but experienced flying instructors. It is believed that the fatal flight was for purpose of stall checking at 4000 ft. Control was obviously lost with one witness stating that aircraft appeared to perform an aerobatic manoeuvre.
It was known that on previous flights that the engine idled at high rpm producing significant torque. The owner had also opted to change the engine centre line angle downwards by three degrees to solve a problem with fitting of the nose cowl. Also one of the pilots who first flew the aircraft reported a severe wing drop at the stall.
Questions: Would a high idle rpm contribute towards a severe wing drop?
With this type of engine, would a significant power application as would normally be applied in a stall recovery, cause a torque roll at low IAS?
Would there be a significant gyroscopic effect if rapid power was introduced as part of a stall recovery - and the nose lowered harshly?
What effect would a three degree lowering of the engine centre line have on aircraft handling near the stall?
The wreckage pattern seems to indicate high angle of descent in a flat attitude. This observation is purely from a media picture of the scene and may well be misleading.
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Genghis,
I concur with your observation.
However, if this fatal is determined to be related to the pilots' being caught out by inexperience in regard the specific mission task, then Hudson raises some interesting points and I can think of a few more as well.
More importantly, if the mission did relate to stall investigation then a general discussion moving into, say, propeller forces and SAS systems on turboprop conversions and the like might be of significant value to the GA fraternity within the membership
Might it be appropriate for Hudson to repost with the basic questions, but de-identified in respect of the fatal accident, either in Test Forum or, perhaps, Tech Forum ? While Test Forum would attract the test specialists, Tech Forum would probably attract the greater readership.
I concur with your observation.
However, if this fatal is determined to be related to the pilots' being caught out by inexperience in regard the specific mission task, then Hudson raises some interesting points and I can think of a few more as well.
More importantly, if the mission did relate to stall investigation then a general discussion moving into, say, propeller forces and SAS systems on turboprop conversions and the like might be of significant value to the GA fraternity within the membership
Might it be appropriate for Hudson to repost with the basic questions, but de-identified in respect of the fatal accident, either in Test Forum or, perhaps, Tech Forum ? While Test Forum would attract the test specialists, Tech Forum would probably attract the greater readership.
Alternative wording?
It isn't inappropriate to post as Sussit did, asking about known factual detail, and I'd prefer to leave the thread here, even if it then quietly withers. However, below I've put a suggested re-word of Hudson's first post, which I'd suggest if you wish you repost (and I have no views on whether you care to leave my version untouched, or change it - your call) in your own name on Tech Log or elsewhere.
G
I've been thinking about the subject of stall testing, and particularly that many of us as experienced pilots may be asked to undertake some - particularly on a homebuilt of some flavour. This has raised some fundamental questions in my mind...
The first set of questions are to do with the specific stalling characteristics of such an aircraft. What effect are the following likely to have upon the stalling (and post-stall / stall recovery) characteristics of a light single?
- High torque or high power, either throughout the stall, or applied during recovery?
- Altering of the thrustline?
- Turbo-prop versus piston-prop?
Secondly, most of us understand stalling pretty well, but what are the special issues a flight-test-trained crew would (should?) be covering, that the rest of us might not think about?
G
I've been thinking about the subject of stall testing, and particularly that many of us as experienced pilots may be asked to undertake some - particularly on a homebuilt of some flavour. This has raised some fundamental questions in my mind...
The first set of questions are to do with the specific stalling characteristics of such an aircraft. What effect are the following likely to have upon the stalling (and post-stall / stall recovery) characteristics of a light single?
- High torque or high power, either throughout the stall, or applied during recovery?
- Altering of the thrustline?
- Turbo-prop versus piston-prop?
Secondly, most of us understand stalling pretty well, but what are the special issues a flight-test-trained crew would (should?) be covering, that the rest of us might not think about?
