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l39parts(at)hotmail.com
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 Posted: Sun Nov 02, 2008 9:21 am Post subject: Service Bulletins |
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You stumbled across the truth here C but apparently didn't recognize it. If Piper or Cessna issues an airworthiness directive C owners in the US are required to comply with it and almost invariably do. However C when Piper or Cessna issues a service bulletin C owners in the US often do not comply with it C and are under no legal obligation to do so to keep flying.
A great many SBs are issued by US airplane manufacturers at the behest of their legal department in an effort to limit liability and sell lots of expensive parts. The FAA reviews these and can make them into an AD C with mandayory compliance C if the FAA feels it has merit.
Non-certified aircraft in the US can not have an AD and so it is difficult for owners to know if they should comply.
Others will probably challenge the statement about ADs for experimental aircraft. Instead of telling us what you think- post ONE example of an AD to an experimental aircraft to receive an apology from me for being wrong.
From: richard.goode(at)russianaeros.com
To: yak-list(at)matronics.com
Subject: Service Bulletins
Date: Mon C 1 Sep 2008 17:25:43 +0100
I have been asked to give more detail about the specific problems that led to Yak-52 Service Bulletins. However it is not so simple.
As I have said before there are thirty-one of these covering what C I believe C Yakovlev would term "potentially serious airframe defects". Of course I have a list of these thirty-one; I have seen examples of each physically on an aeroplane C but have no detailed background as to why each of the 31 was introduced. However I have sat through several sessions at Yakovlev in Moscow discussing Yak airframe issues C particularly for 50 and 52 and I HAVE seen a wide range of technical reports and associated photographs showing REAL airframe failures. For the 50 C these were serious and led to four fatal accidents and there would have been a number more had it not been for very vigilant technicians C and an extremely vigorous inspection regime.
For 52s C I have seen evidence (at the meetings above) of failure in a number of areas C including wing mounting brackets; aileron mounting brackets; detachment of elevator balance weights etc. Although I cannot provide a detailed explanation and background for each of the thirty-one SBs (and I cannot believe that anyone would expect me to) I can assure any 52 Owner that each was a real issue; was taken very seriously C and ended with an appropriate Service Bulletin.
It surprises me that there seems to be a significant body of 52 Owners who seem to regard these SBs as being discretionary. I assume that if Piper or Pitts issue an Airworthiness Directive C then the Owner will ensure that their aeroplane complies to that AD. What I find puzzling is that the same approach seems not to apply with Russian aircraft.
Clearly there is a difference in that the Russian aeroplanes are not Normal Category and Certificated aircraft in the USA. Nevertheless C surely one assumes that the Service Bulletins are just as vital for aircraft safety.
There also seems to me to be a suggestion that Yakovlev promulgated SBs for reasons other then those purely related to safety. I know Russia better than most C and few things surprise me about Russia but C from a combination of my own experience and simple logic C I can see no foundation for such thinking. The key points are surely:
- Yakovlev is a Design Bureau C and has no role in the manufacture or subsequent modification of its aircraft.
- So Yak design aircraft C and other C and completely separate C organisations manufacture them C and then build any modification kits etc that might be required.
- So Yak-18T was (and is) built in Smolensk; 52 at Aerostar in Romania; 50 and 55 at the State Factory at Arsenyev in the extreme Russian Far East.
- In addition the vast majority of these Service Bulletins were issued in Soviet days C when Yakovlev C and indeed the whole Soviet aircraft industry was well-funded. All 18T Bulletins were finished by 1984; all Yak-50 Bulletins by 1985 C and the last significant 52 Bulletin (SB number 107) in 1990.
- When these SBs were promulgated by Yakovlev C they only did the design and practical work for one prototype. At that stage the manufacturing unit was then required to make whatever modification kits were required C and then installed by appropriate technicians.
- None of this benefited Yakovlev C and I suspect C not good news for them C since it clearly would not reflect well on their capabilities as aircraft designers if their designs needed constant modifications. So I think we can be sure that Yakovlev only issued SBs when they regarded them absolutely necessary! For further information please see the attached links below.
http://www.russianaeros.com/Yak52service.htm
http://www.russianaeros.com/Yak-55%20Service%20Bulletins.htm
http://www.russianaeros.com/Yak-50%20Service%20Bulletins%20after%20crashes.htm
Richard Goode Aerobatics
Rhodds Farm
Lyonshall
Herefordshire
HR5 3LW
United Kingdom
Tel: +44 (0) 1544 340 120
Fax: +44 (0) 1544 340 129
www.russianaeros.com
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wlannon(at)persona.ca
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| Posted: Sun Nov 02, 2008 11:01 am Post subject: Service Bulletins |
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Hi Ron;
Aircraft manufacturers do not (in fact can not) issue an Airworthiness Directive. That is the prerogative of the state and carries the force of law.
What the manufacturer often does is issue what they call a "mandatory" Service Bulletin. Of course it is not mandatory but serves their main interest of liability protection.
Cheers;
Walt
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