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Stressmerchant
Joined: 28 Oct 2014
Posts: 22
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 Posted: Sat Feb 26, 2022 12:17 am Post subject: Accident report from Australia |
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After several years, the Australian Transport Safety Bureau (ATSB) have finally issued the report for the Yak-52 accident off Brisbane. I've attached a copy to this post.
I guess the investigation was unlikely to find a definitive cause, given that there was no recorded flight data, the impact was not witnessed, and a significant amount of the wreckage was not recovered. Having said that, I am a little disappointed in the report, especially given the length of time it took to be released.
Two aspects do interest me. The one is the issue of the fatigue life of the aircraft. My understanding was that the fatigue life is extended through the maintenance program and specific inspections. Noting the report statement that "At the time of publication, and with the exception of some aircraft that have been modified to a tail-wheel configuration, the remaining Yak-52s registered in Australia had exceeded their airframe life", ATSB seem to assume that no inspections have been taking place.
The second is the issue of the bellcrank. My understanding was that the aluminium bellcrank required a recurring inspection, but that the requirement for the inspection terminated if a steel bellcrank was fitted. The ATSB report suggests that the inspection is required irrespective of the bellcrank fitted. Could someone who has more knowledge of the requirement comment in this?
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| Description: |
| ATSB accident report for VH-PAE Yak-52 |
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ao-2019-027-final.pdf |
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2.54 MB |
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257 Time(s) |
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richard.goode(at)russiana
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| Posted: Sat Feb 26, 2022 1:09 am Post subject: Accident report from Australia |
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Hello Mike,
I think I'm right in saying that the yak-list can't accept attachments, but I'd be most grateful if you could send me an email with that attachment.
Then in terms of fatigue life that is interesting. If they are saying that all 52 in Australia have exceeded their airframe life, one would assume that they are all being grounded. The practicality is that the situation is possibly correct in that in original Russian legislation, the 52 had a 600 hour airframe "life". To an extent this is due to the fact that the aircraft sat at one airfield and did nothing but aerobatics and sometimes it quite hard G. But also that they were employing 250 million people in a quasi-military environment and needed work for them. So after 600 hours every aircraft would go back to a manufacturing factory; totally dismantled to its components and then rebuilt as a new aircraft. When we started importing them into Europe (and indeed elsewhere) we initially used a very "Mickey Mouse" registration which had no legal validity, but the various aviation authorities accepted them for about 14 years before clamping down.
And of course the 52 is non-certified, and therefore there is no internationally accepted paperwork for the aircraft allowing it to automatically be registered in any country. So it is totally up to the local aviation authorities in each country whether to allow it to fly there. In the UK we have strange, but very helpful part of our aviation legislation whereby any aircraft that is airworthy and "ex-military" will be given a "permit to fly" – i.e. restricted certification. But after a while UK CAA realised that there was the 600 hour "lifetime" affecting all 52 and were we going to follow it? Clearly that would have been economically absurd, so we organised a series of meetings between ourselves; UK CAA and Yakovlev in Moscow, which after a lot of discussion ended up with a new system of lifetime whereby every aircraft had a detailed inspection every 600 hours or 15 years.
This meant that engine was removed; wings removed tail et cetera but only sufficiently to be able to NDT test all the structural parts. And of course a variety of other checks on different parts of the aircraft, but dramatically less than the total reconstruction which the Russians did. In terms of cost, this rather depends who does it, but around £7000, so not absurd every 15 years. And, for the time being, there has been a 3500 hour limit, but with a general understanding that that could be extended.
But clearly owners in Australia need to have the situation clarified, in case there is suddenly some edict grounding the aircraft! However many countries in Europe, and indeed elsewhere have followed the UK 52 lifetime procedures.
For the bellcrank, for strange reasons, the Russians, I believe, never made it mandatory to change but strongly advised. Then, in terms of how this is interpreted comes down to the fact that there is no international legislation for a 52 and it's up to each individual country to make up their own rules. But certainly the understanding is that if still aluminium it must be regularly checked but, I believe, is steel that requirement stops.
RICHARD GOODE AEROBATICS
Rhodds Farm, Lyonshall, Hereford, HR5 3LW, UK
Tel: +44 (0)1544 340120 Fax: +44 (0)1544 340129
e-mail: richard.goode(at)russianaeros.com
www.russianaeros.com
WORLD LEADERS IN RUSSIAN SPORTING AIRCRAFT & ENGINES
In partnership with Aerometal Kft, Hungary.
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Stressmerchant
Joined: 28 Oct 2014
Posts: 22
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Stratyaks
Joined: 02 Nov 2015
Posts: 9
Location: Stratford upon Avon
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| Posted: Mon Feb 28, 2022 2:34 am Post subject: Re: Accident report from Australia |
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In the UK we are subject to a mandatory 600hr Life Extension programme. That is at 600 hours flying time OR 3,500 Landings OR Ten years calendar life. Wings off: fuel tanks out and ailerons off. Tailplane off: horiz and vert plus elevators and rudder. Main and nose gear off and finally, Engine bearers off.
The various attachment points are given a thorough visual inspection as are various noted areas inside the wings (hence tanks out). All the main attachment points are also given a NDT inspection as are all the attaching bolts (AMOC, they can be renewed) but the aileron bolts MUST be renewed.
Its quite intense. We got caught on calendar time, we were nowhere near the landings or flying hours allowed.
Elevator pulley. A couple of years ago I found cracks in ours exactly like the ones in the example shown in the accident report and changed our to a steel pulley using a CAA Minor MOD (however there was debate as to whether, in fact, it should have been a Major MOD) anyway, ours was Minor this means we have to continue to perform the annual crack inspection regardless. Had we gone down the Major MOD route AND the CAA had agreed to it and written it into the MOD . . . we might have been able to discontinue the annual pulley inspection but, to be frank, it doesn't take long to do and you have the fairings off anyway so it is no real burden.
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maryAidan
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| Posted: Tue Apr 23, 2024 7:37 pm Post subject: Re: Accident report from Australia |
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The statement in the report suggests that there may have been concerns about the adequacy of these inspections and maintenance practices, especially considering that most Yak-52s in Australia had exceeded their airframe life at the time of publication. This raises questions about the effectiveness of the maintenance programs in place for these aircraft. strands
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