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1. 11:58 AM - Throttle Cable Support Incident (Mark Fox)
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| Subject: | Throttle Cable Support Incident |
Hello group,
I am sharing this event in hopes it may help others from having the same
situation.
I have a Pulsar XP, Rotax 912, built from 1994 -1996, SN 373 with 1050
hours on it. I am sure others have experienced this too, but when you do a
1- minute run up to check the engine and shut it down, it can sometimes
want to continue to run/diesel (if you will) when it has only run for 1
minute.
I have learned if you add a little power over idle then quickly pull the
power as you turn the key off it shuts down a lot cleaner. So that has been
my procedure.
Here is what happened last week. I did the 1-minute run up, pulled the
power and turned the key off at the same time as usual.
The engine went to full throttle instantly. Yikes !!!!!I
I tried to pull the power back to the stop (already there), applied full
brakes, and turned the fuel selector off all in about 1-3 seconds. In that
3 second time frame, which happened so fast, I thought I would fly
through the neighbor's hangar, destroy myself, the airplane and his
helicopter...but luckily I didn't. In my mind I know the brakes can't hold
it and the engine will run for 8 min with just the fuel in the carbs at
idle...I have no idea how long at full power, that's what ran through
my head in seconds. WTF do I do ?
It was 3 seconds of scary shit.
I (think) I turned the ignition key off multiple times then luckily it shut
down.
Upon inspection here's what happened:
1 - Moving the throttle back relatively abruptly on shutdown broke the
throttle cable support bracket on the side of the fuselage. It's the
support bracket guide on the side of the fuselage forward of the throttle
cable - built exactly to aerodesign specs.
2 - When the support broke, it allowed slack in the cable housings,
allowing the engine to go to full throttle. I actually didn't know this
would/could happen.
3 - FORTUNATELY, the sudden full power had so much left torque on
the airplane the nose wheel turned 90 degrees to the left.
I believe now that the nose wheel being 90 degrees to the center line is
the only thing that stopped me from flying through the neighbors hangar. It
acted as a chock. (Yes I was pointed safely down the taxi way before this
happened)
4 - While repairing the bracket, I was surprised it was only microed to the
fuselage, no glass at all. That is what the aerodesigns called for
apparently as I did not deviate at all from the manuals.
Bottom line, check your cable support brackets and reinforce with glass if
you don't have it...mine has about 12 layers now :)
Thanks
MLF
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