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Old 11th Jan 2015, 02:25
  #46 (permalink)  
Kharon
 
Join Date: Oct 2010
Location: Styx Houseboat Park.
Posts: 2,053
I'll try again.

I have cherry picked the following quotes from AO-2013-051 as they answer some of the questions which the Uscinski coroners report omitted. I expect those answers are in the 'reports' tabled, but without being able to see them, my curiosity bump is driving me nuts. There are some interesting parallels, not only in relation to the accident; but to the reports and findings.

Spitfire - Fatal #1.

By now the pilot had turned right and the Spitfire was near the extended runway centreline and 1 km from the runway threshold at a slow speed. A left turn was then observed and, soon after, a wing dropped and the aircraft entered a steep descent. The aircraft crashed in a factory car park, fatally injuring the pilot and substantially damaging the aircraft.
The aircraft was prone to aerodynamically stall with little or no aerodynamic precursors and it was not fitted with a stall warning device, increasing the risk of inadvertent stall.
Maximum take-off weight for non-aerobatic flight was 810 kg.
Operating data provided for the aircraft type listed the stall speed with wing flap retracted as 54 kt, and with wing flap and landing gear extended as 45 kt (assuming 1 g flight).
At the time he noted that in the landing configuration, after initial slight buffeting and hesitation, the left wing dropped suddenly. He also noted that normal recovery techniques were effective
Shortly after the stall testing, the owner conducted in-flight calibration of the airspeed indicator using reciprocal courses with GPS ground speed data and found that the indicator was under-reading by about 8 kt. On that basis, the owner recorded the actual stall speeds as 63 kt with wing flap and landing gear retracted, and 57 kt with them extended.
The replica Spitfire kit manufacturer advised that their test pilots had found the aircraft type to be stable at low speeds and that a wing drop would only occur if left or right aileron was applied. Under flight test conditions, the average height loss during stall recovery was reported to be 200 ft.
Spitfire-Fatal #2.

"Mr Soutter noted that from the time of manufacture, the aircraft was overweight for the RA-Aus category it was assigned to. He said this would have resulted in a situation, which required the aircraft to be flown at speeds other than those prescribed in the aircraft’s Flight Manual". WTF?
Was this data in reports? :call it an apple or call it an orange, but the stall speed (range) is the stall speed, is the stall speed.

With reference to the Flight Manual, this aircraft would have had adverse handling characteristics with 8.1kg of tail ballast and a battery which had been moved aft of its original position.
Theoretically correct, but where - roughly – was the CG and what was the real weight at the time. Should there not be at least a back of a matchbox calculation to support the assertion?.. Was this data contained in the reports provided the coroner? Was there a table or graph to show the basic weights; or, where the CG was located, the usual stuff BEW + whatever v MTOW: ATOW : MLW v ALW with the CG 'defined' as being @ between X-Y. Curious thing, even if it was guestimated it would resolve some of the issues...Forget the smoke about 'category', the questions unanswered are, was the aircraft (a) over MTOW weight or (b) out of CG?. Seems to me this matters, has anyone worked this out?; is it in one of the reports?.

With this being the second fatal, making two out of 17 (<12%) aircraft I find it disconcerting that the ATSB said:-

"The ATSB noted that the complete decoding / detection / deciphering of the parameters was outside the scope of their assistance to the RA Aus investigation, so it was not performed."
Has there been an owners and pilots pow-wow with some serious discussion related to mitigating the risk of this event reoccurring?, have both ATSB and CASA contributed expert advice to that discussion?

Just asking and no, I don't have a dog in this fight but; it appears 'prima facie', that the reports are 'fluffy', padded and no real risk mitigation strategy has been provided. Well, not in the documents I've read at least. I expect the RA-Aus troops have got it all sorted out and I'm just suffering from chronic curiosity – again.

Right then, back to my knitting.

Last edited by Kharon; 11th Jan 2015 at 02:40.
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