---------------------------------------------------------- Yak-List Digest Archive --- Total Messages Posted Fri 03/25/11: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 10:45 AM - Yak-52 elevator failure (Richard Goode) 2. 12:03 PM - 18T torque (Joe Howse) 3. 07:37 PM - Re: Yak-52 elevator failure (Cliff Coy) ________________________________ Message 1 _____________________________________ Time: 10:45:35 AM PST US From: "Richard Goode" Subject: Yak-List: Yak-52 elevator failure To answer the queries of several people who have written to me directly: =D8 I have passed on all that I know today ' but it seemed to me that this is a critical issue that any sensible owner would want to check on their own aircraft. =D8 I understand from Yakovlev themselves that they will issue a formal Service Bulletin (AD). =D8 Again I understand that this will be made out of steel rather than aluminium alloy. =D8 However I do not know any more details of when/where the plate might be made etc. =D8 I have no idea if there would be a potential similar problem with the 18T/50 etc, which have a similar design. Richard Goode Aerobatics Rhodds Farm Lyonshall Herefordshire HR5 3LW United Kingdom Tel: +44 (0) 1544 340120 Fax: +44 (0) 1544 340129 www.russianaeros.com ________________________________ Message 2 _____________________________________ Time: 12:03:51 PM PST US From: "Joe Howse" Subject: Yak-List: 18T torque Anyone have a torque chart for the 18 Joe ________________________________ Message 3 _____________________________________ Time: 07:37:30 PM PST US Subject: Re: Yak-List: Yak-52 elevator failure From: Cliff Coy *Cracking in this area has been a known issue for many years. The contributing factors seem to be: Incorrect elevator cable tension Incorrect elevator travel and ~sigh~ abuse of the machinery.... These conditions allow for the elevator counterweight to strike the horizontal stabilizer and/or up inside the vertical stabilizer. This places a bending moment between the counterweight arm and the elevator whose weakest point is exactly as Richard has shown. If rapid movement to the elevator stop produces a hard knocking slap, inspect and repair immediately. I'm sure the change to steel will alleviate any work hardening issues that the aluminum horns may be developing, but the contributing factors above will not stop this kind of failure, it'll just move the failure to a different point- like the counterweight bolts or center elevator bearing. If nothing else, I'm glad to see the horns are available. How are you addressing match drilling to each individual counterweight? Thanks Richard! Cliff * On Fri, Mar 25, 2011 at 13:16, Richard Goode wrote: > To answer the queries of several people who have written to me directly: > > > =D8 I have passed on all that I know today ' but it seemed to me that this > is a critical issue that any sensible owner would want to check on their own > aircraft. > > =D8 I understand from Yakovlev themselves that they will issue a formal > Service Bulletin (AD). > > =D8 Again I understand that this will be made out of steel rather than > aluminium alloy. > > =D8 However I do not know any more details of when/where the plate might be > made etc. > > =D8 I have no idea if there would be a potential similar problem with th e > 18T/50 etc, which have a similar design. > > > Richard Goode Aerobatics > > Rhodds Farm > > Lyonshall > > Herefordshire > > HR5 3LW > > United Kingdom > > > Tel: +44 (0) 1544 340120 > > Fax: +44 (0) 1544 340129 > > www.russianaeros.com > > > * > =========== =========== =========== =========== > * > > -- Clifford Coy Border Air Ltd. 629 Airport Rd. Swanton, VT 05488 802-868-2822 TEL 802-868-4465 FAX Skype: Cliff.Coy ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message yak-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Yak-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/yak-list Browse Digests http://www.matronics.com/digest/yak-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.