On 7/29/2024 4:52 PM, Samuel Ajayi via KRnet wrote:
There is nothing wrong with "high speed taxi test".
+++++++++++++++++++++++++++++++++++++++++++++++++++++
I for one do not recommend long hours of high speed taxi testing on any
airplane, new or one with 1000 hour of air frame time. I consider it
unnecessary exposure for an accident. That however is not what happened
here. Let's put it in perspective.
Zach was not doing a high speed taxi test when he experienced the brake
fire but it did point out a potential problem when using "plastic" brake
lines. Zach had installed a 360 degree camera on the left wing on an
extended probe. The weather was such as it restricted flight so he
wanted to taxi and see how the camera performed. From the video I saw
it appears he taxied a mile or more from the hangar to shoot video and
when he noticed a problem he was taxiing back to the hangar. If 211LF
did not have such positive steering control on the ground he most likely
would have had to stop before the brake got hot enough to catch fire.
The positive control allowed him to overcome the dragging brake as he
headed for the hangar. A tri-gear with brake steering would have only
gone in circles. 211LF has passed the 1000 hour mark without a previous
problem. My home base for many years has an 8000 foot runway so long
taxi runs are not normally a problem for 211LF.
The lesson to be learned here is "do not use nylon line all the way to
the brake puck, regardless of the landing gear setup". 1 hour or 1000
hours, you could have a problem. The problem is most likely to develop
in the early hours of testing with lots of taxi testing and braking but
as happened here, it can happen any time. I flew for 800 hours without a
fire extinguisher. Zach was smart enough to carry one and it saved the
airplane. The only thing I would suggest, in hind site, is maybe never
exhaust the complete fire extinguisher in one shot. Save a bit it if
re-ignites.
I spoke with the local fire chief and he claimed they arrived in 3 1/2
minutes and there was still a hot spot (under the wheel cover? ) they
detected with infrared camera and finished the job. 211LF survived to
fly another day. Some might suggest this was to fulfill the request in
the last line of the poem it inspired titled "FLIGHT".
"My only hope, God bless these wings that I might fly again".
All ended well and 211LF is back in the air.
Larry Flesner
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