---------------------------------------------------------- Yak-List Digest Archive --- Total Messages Posted Wed 04/24/13: 1 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 08:24 AM - Re: Re: Re: Hydraulic Lock (Bitterlich, Mark G CIV NAVAIR, WD) ________________________________ Message 1 _____________________________________ Time: 08:24:17 AM PST US Subject: RE: Yak-List: Re: Re: Hydraulic Lock From: "Bitterlich, Mark G CIV NAVAIR, WD" Actually this is very good information to keep in mind, and I am going to chew on the physics of that answer for a day or two. It poses a very interesting study in the stresses involved and should make for a rather intense dinner table debate! :-) (Not you, my engineering friends!) Thanks for writing back Jill. So given this information, what is the advice of M14P.com regarding prop strikes and what should be done to the engine afterwards? Mark -----Original Message----- From: owner-yak-list-server@matronics.com [mailto:owner-yak-list-server@matronics.com] On Behalf Of Jill Gernetzke Sent: Tuesday, April 23, 2013 16:56 Subject: Yak-List: Re: Re: Hydraulic Lock Good feedback, Mark. Most prop strikes occur with wood composite or carbon fiber blades. (We haven't had a prop strike teardown with a metal prop, yet.) The inertia of energy is absorbed by the blades disintegrating or being shaved off. I agree with your assessment of a hydraulic lock on startup, but not when the engine fires and it pulls fuel or oil in from the intake tubes. If it fires, there is a good likelihood that the accessory shaft will twist. At landing speed, the aircraft travels 3.5 feet for each blade in contact with the ground at initial point of contact. As the engine slows, this increases. Consequently, the rearward deflection of a very thin blade exceeds the rotational shearing. Additionally, the reduction of blade length per rotation with a normal flare landing is less than a tenth of an inch. In other words, the wood fails well before any engine parts are stressed to the +400 foot/lbs of torque design load. Jill ------------------------------------------------------------------------------------- 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.