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richard.goode(at)russiana
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 Posted: Fri Oct 26, 2007 5:56 am Post subject: YAk-50 structural issues |
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Yak-50 structural issues
I am concerned that people refer to "the spar mod." There are actually six Service Bulletins relating to the center section and the wings - SB's number 16; 37; 43; 53; 61 (actually further strengthening version of 37); 79.
UNLESS you really know what you are looking for, it is very difficult to confirm the presence of these SB's. Having said that, it is unlikely (but in Russian nothing is impossible) that an aircraft would embody Bulletin 79 without the others.
B79 is relatively easy to confirm in so far as it is a 4.5 mm plate on both top and bottom surfaces of the center section. However, you need to make sure that it is 4.5 mm - B16 is the 3.5 mm plate on the top surface, and I have also seen 3 mm; 4 mm!
For a detailed explanation of the Service Bulletins - and indeed the failures that led to them - please contact us for a document we have prepared and which we will e-mail to anyone interested.
The Yak-50 is actually an extremely strong aircraft, and if flown at +6, -4G will last for ever.
Unfortunately its introduction coincided with aerobatics changing from large graceful manoeuvres to sharp corners, and Russian Team members, in their competitive zeal, regularly exceeded +9 -7G.
In my personal view 50s should not be flown at more than +6 -4 and indeed I can see no reason why anyone would want to fly at higher levels. If you need to do so, then get a 55 or a Sukhoi!
Richard Goode Aerobatics
Rhodds Farm
Lyonshall
Herefordshire
HR5 3LW
United Kingdom
Tel: +44 (0) 1544 340120
Mob: +44 (0) 7768 610389
Fax: +44 (0) 1544 340129
www.russianaeros.com
[quote][b]
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netmaster15(at)juno.com
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| Posted: Fri Oct 26, 2007 12:18 pm Post subject: YAk-50 structural issues |
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Dear Richard, PLease e mail me the referenced document pertaining to the YAK 50 , the early failures,, and the explanation of the Service Bulletins applicable thereto. Specifically,SBs 16; 37; 43; 53; 61 and 79. Thankyou for your generous offer to share this information.
Kindest Personal Regards.
Cliff Umscheid, netmaster15(at)juno ([email]netmaster15(at)juno[/email]) .com
-- "Richard Goode" <richard.goode(at)russianaeros.com> wrote:
Yak-50 structural issues
I am concerned that people refer to "the spar mod." There are actually six Service Bulletins relating to the center section and the wings - SB's number 16; 37; 43; 53; 61 (actually further strengthening version of 37); 79.
UNLESS you really know what you are looking for, it is very difficult to confirm the presence of these SB's. Having said that, it is unlikely (but in Russian nothing is impossible) that an aircraft would embody Bulletin 79 without the others.
B79 is relatively easy to confirm in so far as it is a 4.5 mm plate on both top and bottom surfaces of the center section. However, you need to make sure that it is 4.5 mm - B16 is the 3.5 mm plate on the top surface, and I have also seen 3 mm; 4 mm!
For a detailed explanation of the Service Bulletins - and indeed the failures that led to them - please contact us for a document we have prepared and which we will e-mail to anyone interested.
The Yak-50 is actually an extremely strong aircraft, and if flown at +6, -4G will last for ever.
Unfortunately its introduction coincided with aerobatics changing from large graceful manoeuvres to sharp corners, and Russian Team members, in their competitive zeal, regularly exceeded +9 -7G.
In my personal view 50s should not be flown at more than +6 -4 and indeed I can see no reason why anyone would want to fly at higher levels. If you need to do so, then get a 55 or a Sukhoi!
Richard Goode Aerobatics
Rhodds Farm
Lyonshall
Herefordshire
HR5 3LW
United Kingdom
Tel: +44 (0) 1544 340120
Mob: +44 (0) 7768 610389
Fax: +44 (0) 1544 340129
www.russianaeros.com
_____________________________________________________________
Click to find great rates on health insurance, save big, shop here.
[quote][b]
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mark.bitterlich(at)navy.m
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| Posted: Fri Oct 26, 2007 3:36 pm Post subject: YAk-50 structural issues |
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Hi Richard. Very kind offer, and thanks for the expert advice as well.
Question: I have the list of these Bulletins hidden away someplace, but
not right at hand. Way back when, the original 50's came with a
thermostat installed in the oil cooler. Later on, they came out with a
SB that removed the thermostat and replaced it with an over-pressure
by-pass valve. In Russian helicopters that use the same M-14P, and the
same oil cooler, retain the thermostat.
As you know from personal experience, warming up the oil on a YAK-50, or
any M-14 engine for that matter, on a cold day requires patience.
On that note, last year I managed to acquire one of the original oil
coolers with the original thermostat installed. Just for the heck of
it, I installed that "as is" into the M-14 installed into my YAK-50.
The "plus side" is that it works perfectly. The oil temp comes up very
rapidly to the middle of the green, and then it very slowly drops down
as the valve opens and then slowly comes back up to the middle of the
green again. I am as pleased as punch in how well it works. An
additional factor is that on long descents, the oil temperature always
stays perfectly centered in the green. So it appears to be a win-win
situation. HOWEVER, I know the Russians pulled that thing out for a
reason, and my guess is because if the oil cooler ever becomes clogged
up, it will simply burst OR if it starts to go bad, you will lose oil
pressure to the engine, and then goodbye engine. So to that end, they
replaced the thermostat with the over-pressure relief valve.
You have been around M-14's quite a bit. What is your reaction to me
leaving that thermostat in there? If you think it to be a stupid idea,
then I want to know it and don't mind being told over the net at all. I
always keep a watchful eye on both pressure and temp. I think I could
quickly see any change in what is considered "normal" in either reading.
My real concern is that something happened to make the Russians pull
this thermostat,,, but then... Why keep it in the helicopters?
Best Regards,
Mark Bitterlich
--
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