---------------------------------------------------------- Yak-List Digest Archive --- Total Messages Posted Sun 09/29/13: 4 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 01:00 AM - Re: Hydrostatic tests (Richard Goode) 2. 03:22 PM - CJ Landing Gear Strut pressure (dabear) 3. 07:34 PM - Re: CJ Landing Gear Strut pressure (Jeff D) 4. 07:45 PM - Re: CJ Landing Gear Strut pressure (Walter Lannon) ________________________________ Message 1 _____________________________________ Time: 01:00:24 AM PST US From: "Richard Goode" Subject: RE: Yak-List: Hydrostatic tests Hi Walt, Yes, of course all tests should be done hydrostatically. You are correct that the Russian requirements is to test at 75 bar, but given that the operating range is up to 55 bar, and also that many people only test every three years, or even longer, during which time there is the opportunity for a a lot of corrosion and also the potentially catastrophic consequences of the bottle bursting, my purely personal view is that I want a larger safety margin in the test. I know from Russian sources that the ultimate design pressure is 200 bar, so my view is that, at 100 bar, there is still a lot in hand, and I would rather that it failed at 100 than in my aircraft! Richard Goode Aerobatics Rhodds Farm Lyonshall Hereford HR5 3LW Tel: +44 (0) 1544 340120 Fax: +44 (0) 1544 340129 www.russianaeros.com From: owner-yak-list-server@matronics.com [mailto:owner-yak-list-server@matronics.com] On Behalf Of Walter Lannon Sent: 28 September 2013 17:38 Subject: Re: Yak-List: Hydrostatic tests Richard; I hope you are having that done by a qualified shop using the hydrostatic method. At 100 Bar you are exceeding the allowable test limit if the Russian specs. are the same as Western. That is typically 5/3 X the max operating pressure. However this does not apply to a welded bottle. The CJ6 bottles are welded and the max. hydro test pressure given is 75 Bar. Less than the 83 Bar allowed for a non-welded bottle at the same operating pressure. I assume the Russian bottles are also welded. Walt From: Richard Goode Sent: Saturday, September 28, 2013 1:45 AM Subject: RE: Yak-List: Hydrostatic tests Hi Todd, I can tell you from experience that the real problem in both undercarriages and the high-pressure air bottles is water, and so many Western pilots do not methodically drain the system at least every day. Once water starts getting into the retraction cylinders, they quickly corrode, and while they should have an overhaul life of only six years, this can be dramatically reduced. Equally, I can tell you that we had a yak 50 where the high-pressure bottle blew up while the aircraft was on the ground, causing incredible damage, and certainly would have brought the aircraft down had it been airborne! Again, totally due to water getting inside and corroding the bottle internally. My own leaf is to test the bottle to 100 bar (twice operating pressure) every year! Regards Richard Richard Goode Aerobatics Rhodds Farm Lyonshall Hereford HR5 3LW Tel: +44 (0) 1544 340120 Fax: +44 (0) 1544 340129 www.russianaeros.com From: owner-yak-list-server@matronics.com [mailto:owner-yak-list-server@matronics.com] On Behalf Of Todd McCutchan Sent: 28 September 2013 00:44 Subject: Yak-List: Hydrostatic tests How often is the hydrostatic test of the main and emergency bottles required? Todd McCutchan Fast Aircraft T-34A & Yak-50 Cell - 260.402.1740 Email: todd@fastaircraft.com Skype: tmccutchan Web: www.fastaircraft.com & www.toddmccutchanairshows.com http://www.matronics.com/Navigator?Yak-List http://forums.matronics.com http://www.matronics.com/contribution -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. href="http://www.matronics.com/Navigator?Yak-List">http://www.matronics.com/ Navigator?Yak-List href="http://forums.matronics.com">http://forums.matronics.com href="http://www.matronics.com/contribution">http://www.matronics.com/c -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. ________________________________ Message 2 _____________________________________ Time: 03:22:52 PM PST US From: "dabear" Subject: Yak-List: CJ Landing Gear Strut pressure What is the CJ6A strut pressure for the Nose and main landing gear? Bear ________________________________ Message 3 _____________________________________ Time: 07:34:51 PM PST US From: "Jeff D" Subject: Re: Yak-List: CJ Landing Gear Strut pressure just did the mains =93 705 psi. Sorry have to check the book for the nose Jeff From: dabear Sent: Sunday, September 29, 2013 4:20 PM Subject: Yak-List: CJ Landing Gear Strut pressure What is the CJ6A strut pressure for the Nose and main landing gear? Bear ________________________________ Message 4 _____________________________________ Time: 07:45:49 PM PST US From: "Walter Lannon" Subject: Re: Yak-List: CJ Landing Gear Strut pressure Nose 20 +/- 1 Bar (294 +/- 14.7 psi), Mains 48 +/- 1 Bar (705 +/- 14.7). Walt From: dabear Sent: Sunday, September 29, 2013 3:20 PM Subject: Yak-List: CJ Landing Gear Strut pressure What is the CJ6A strut pressure for the Nose and main landing gear? 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