There have been some good comments and individual examples of good running engines with fatal flaws and engines that have run well past TBO. As an engineer I am well aware of ‘infant-mortality,’ and also the more common idea that if something is operating well ‘don’t fix it.”
The EAA article on TBO is part of a longer running series on Reliability-Centered Maintenance, a program reportedly now used by the airline industry and the military. More specifically the EAA article on engine TBO drew on five years of data covering the years 2001-2005 for small piston airplane accidents attributed by the NTSB to engine failure. The data shows a steady and rapid decline in engine failure accidents both as Hours Since Overhaul and Years Since Overhaul. Only after 3,000 hours and/or 25 years does the accident rate begin to pick up. What the NTSB data cannot show is much about failures beyond TBO as most engines are overhauled at the point. Assuming that engines failures will begin to increase at and beyond TBO produces a bathtub shaped failure curve. To stay out of the presumptive wear out zone we overhaul our engines which puts us back into the infant-mortality zone. What to do? Maybe find an airplane with about 1,000 hours on the engine and operate it for 1,000 hours. That is what the data ‘suggests.’ J From: [email protected] [mailto:[email protected]] On Behalf Of Donald Sent: Tuesday, February 16, 2010 12:24 PM To: [email protected] Subject: [ercoupe-tech] Re: Engine TBO But, to play the devils advocate, that crack did not just magically appear at some determined TBO. There are schools of thought that also show a good running engine should not be tampered with, you also run the risk of problems in the overhaul. One of the members of this group just had a catastrophic engine failure, with crank busted, at like 300 hours SMOH, but we would not want to therefore become believers that one should overhaul at 300 hrs. I am aware of MANY engines that have run to the neighborhood of twice TBO with no problems. --- In [email protected] <mailto:ercoupe-tech%40yahoogroups.com> , "Jerry Eichenberger" <jeichenber...@...> wrote: > > Jerry - > > My story about TBO was that about 30 years ago I was in a group that owned an > Aztec and Bonanza. The Bonanza was at TBO. Against my wishes, the group voted > to go another 100 hours. The engine was running like a Swiss watch, burned > almost no oil, compressions were excellent; you get the idea. > > After that 100 extra hours, most of the group wanted to go another 100. I put > my foot down and said to either overhaul it or buy me out. We overhauled it. > > The crankshaft had a crack 270 degrees around the circumference. Who knows > how long the crack had been there, but it was likely to have catastrophically > failed within that next 100 hours had we not torn down the engine. > > Hence, I'm a a believer in TBO. What little do you gain by assuming that the > innards of the engine are OK just because compression and oil burn are good? > > Jerry E. > -----Original Message----- > From: [email protected] <mailto:ercoupe-tech%40yahoogroups.com> > [mailto:[email protected] <mailto:ercoupe-tech%40yahoogroups.com> > ]On Behalf Of Jerry Ward > Sent: Monday, February 15, 2010 5:14 PM > To: [email protected] <mailto:ercoupe-tech%40yahoogroups.com> ; > Roy Stubbs > Subject: Re: [ercoupe-tech] Engine TBO > > > I just read the article and it appears to me that they are on to something > smart. I would hope that the FAA would read this and change the way engines > are overhauled. I would hate to have to overhaul a perfectly good running > engine that is strong and has good compression and seems to not burn too much > oil. It appears that the fresh engines are the ones to worry about. Jerry in > the Great Northwest. > > --- On Mon, 2/15/10, Roy Stubbs <rdstu...@...> wrote: > > > From: Roy Stubbs <rdstu...@...> > Subject: [ercoupe-tech] Engine TBO > To: [email protected] <mailto:ercoupe-tech%40yahoogroups.com> > Date: Monday, February 15, 2010, 1:02 PM > > > > > Has anyone on the list read this month’s EAA Sport Aviation’s article > “Is Engine TBO a Myth?â€? > > > > Wonder what your thoughts might be? > > > > From: ercoupe-tech@ yahoogroups. com [mailto:ercoupe- t...@yahoogroups .com] > On Behalf Of Roy Stubbs > Sent: Monday, February 15, 2010 8:55 AM > To: 'Jack Burwell'; 'Ronald Hynes'; 'earl johnson' > Cc: ercoupe-tech@ yahoogroups. com > Subject: RE: Fw: RE: [ercoupe-tech] Floor board removal > > > > > > Mine are also made up of two pieces and have the rudder pedal assembly which > needs to be removed before the floor boards can be removed. The only way it > is accomplished is my 5’6†125# son and pilot buddy. > > > > From: ercoupe-tech@ yahoogroups. com [mailto:ercoupe- t...@yahoogroups .com] > On Behalf Of Jack Burwell > Sent: Sunday, February 14, 2010 3:08 PM > To: 'Ronald Hynes'; 'earl johnson' > Cc: ercoupe-tech@ yahoogroups. com > Subject: RE: Fw: RE: [ercoupe-tech] Floor board removal > > > > > > Mine are made up of 2 pieces but they are still an absolute nightmare to > remove and reinstall. > > -----Original Message----- > From: ercoupe-tech@ yahoogroups. com [mailto:ercoupe- t...@yahoogroups .com] > On Behalf Of Ronald Hynes > Sent: Sunday, February 14, 2010 12:54 AM > To: earl johnson > Cc: ercoupe-tech@ yahoogroups. com > Subject: Re: Fw: RE: [ercoupe-tech] Floor board removal > > > > I will always admire old Henry Ford and his way of thinking. When he would > have a difficult problem with manufacturing his autos, he was said to assign > the problem to the lazyest of his employees because if they could not find a > better way to fix the problem then there wasn't a better way. After 40 years > of owning and driving Fords, I follow Henry's idea and I simply ask my sons. > Never fails me. > > Ron Hynes, Alberta Canada > > > > > --- On Sat, 2/13/10, earl johnson <johnsonec2000@ yahoo.com> wrote: > > > From: earl johnson <johnsonec2000@ yahoo.com> > Subject: Fw: RE: [ercoupe-tech] Floor board removal > To: "Tech-Ercoupe Group" <ercoupe-tech@ yahoogroups. com> > Received: Saturday, February 13, 2010, 2:00 PM > > > > > > i have seen a Ercoupe with Floor Board made up of two pieces,not sure if it > legal > > however i have been thinking about doing that sure would make under the floor > board > > service easier. > > > > > > --- On Sat, 2/13/10, jackburwell2619@ comcast.net <jackburwell2619@ > comcast.net> wrote: > > > From: jackburwell2619@ comcast.net <jackburwell2619@ comcast.net> > Subject: RE: [ercoupe-tech] Floor board removal > To: "'rurndum'" <rurln...@smith- valley.com>, ercoupe-tech@ yahoogroups. com > Date: Saturday, February 13, 2010, 2:00 PM > > > > I just went through the process assisting with the annual and it's a real > pain having to remove the brake pedal and an even bigger pain reinstalling it > and the boards. > > > > -----Original Message----- > From: ercoupe-tech@ yahoogroups. com [mailto:ercoupe- t...@yahoogroups .com] > On Behalf Of rurndum > Sent: Saturday, February 13, 2010 12:37 PM > To: ercoupe-tech@ yahoogroups. com > Subject: [ercoupe-tech] Floor board removal > > > > I helped with an annual inspection yesterday on a '46 C Model. Removing the > floor board was a pain because of the brake pedal being attached to it. Is > there a modification to make the floor removal easier? > > Thanks! > > Jack > > > > > > > ---------------------------------------------------------- > > Yahoo! Canada Toolbar : Search from anywhere on the web and bookmark your > favourite sites. Download it now! >
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