I test fly experimental aircraft professionally. There are arguments both ways on whether or not to do high speed taxi test. I had an incident about two months ago where the client said the airplane was ready to go. It looked ready but my policy is that I don’t test fly without high speed taxi test. Everything went well until I pulled the engines back from a full power run down the runway and both engines quit simultaneously. I was told that I probably pulled them back too fast. So on the next pass down the runway an engineer was sitting in the right seat and we lifted off and I eased the power back very slowly only to find that both engines shut down again. Obviously this was a problem that I was glad had happened while over the runway rather than away from the airport. Turns out it was a manual to electronic handoff of the throttles and when power was reduced while at speed the props would windmill causing the electronics to sense a problem and thus shut both engines down. The engineers looked at it then redesigned the electronics which solved the problem. Bobby Ibrahim was a close friend of mine that died a year ago on a test flight. Had he done a high speed taxi first he would have found the airplane to be unsafe to fly and would not have gotten killed.
Pilots do things differently but for me I’m sticking with what has kept me safe for all these years. I won’t fly a new plane until I’ve done runway hops. Victor Taylor > On Jul 29, 2024, at 17:52, Samuel Ajayi via KRnet <krnet@list.krnet.org> > wrote: > > > I disagree with this notion. There is nothing wrong with "high speed taxi > test". There is no certified production aircraft that has not gotten through > that testing phase. High speed taxi will accomplish several items that must > be determined as part of the certification process. For example, how > maneuverable is the aircraft on landing or takeoff roll and what is the > braking distance from the time you identify an emergency and apply brakes to > the time the aircraft come to a stop. Will the temperatures exceed > sub-component rating? Based on your weight and speed, you may not be able to > stop the aircraft in sufficient time and may have to commit to take off. > These are just a few things you need to understand/consider on a one-off type > design. > > What is critical to understand is brake temperature and what cool down period > should be observed between each attempt. If component manufacturer does not > provide such information, then is it left to the aircraft > manufacturer/builder to determine what those should be. There are many > things to determine at the onset to figure out which component drives your > temperature consideration. > > Unfortunately, light GA airplanes don't typically have a probe at the wheel > to give instantaneous temperature reading. A small infrared temperature from > Amazon should do the trick. Stop and get out of the aircraft or have someone > point it at the inboard portion of the wheel or caliper. Because most > builders don't install wheel pants until much later, this issue may not > manifest if at all. > > Just a thought. > > From: KRnet <krnet-boun...@list.krnet.org> on behalf of MS > <propbala...@att.net> > Sent: Monday, July 29, 2024 1:38 PM > To: Larry Flesner via KRnet <krnet@list.krnet.org> > Subject: Re: KRnet> KR Wheel Fire Write Up > > The story provides a great illustration of the good sense of not doing "high > speed taxi texts" and the using of brakes for anything except holding and the > occasional short runway. > > Mike Stirewalt > KSEE > > -- > KRnet mailing list > KRnet@list.krnet.org > https://list.krnet.org/mailman/listinfo/krnet
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