king air undercarriage problem
king air undercarriage problem
(OP)
Any King Air 300 experts out there??
Problem with a b300, undercarriage will not retract. This happens erratically and may go weeks without problem. UC selected up, gear starts to retract and then stops, cb blows after 15 secs. Crew reset cb and retract gear succesfully. No other faults on system. Have changed squat switches and bled system.
Anybody got any other suggestions??
Thanks
Problem with a b300, undercarriage will not retract. This happens erratically and may go weeks without problem. UC selected up, gear starts to retract and then stops, cb blows after 15 secs. Crew reset cb and retract gear succesfully. No other faults on system. Have changed squat switches and bled system.
Anybody got any other suggestions??
Thanks





RE: king air undercarriage problem
Logical next step is block it up on the ground, put an ammeter on the circuit, watch what's going on during a retract cycle, try to correlate excessive current draw with portions of the cycle, and start looking for stuff that's binding/ bent/ ungreased/ cracked, whatever.
Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA
RE: king air undercarriage problem
RE: king air undercarriage problem
The CB popping is a bit misleading as the system is designed to do this.
It uses an electric motor driving the pump through a powerpack assembly. The motor is protected by a 60amp (auto resetting) CB, which also provides power to the motor relay via a 5 amp CB and also the landing gear control circuit which includes switches on the selector handle, solenoids on the powerpack to a shuttle valve and also a timer circuit board. If the pump runs for more the 15 seconds the timer board shuts it down by popping the 2 amp CB. This is what happens at random times - it may go a month without fault and then may fail twice in 2 days. It seems like when the fault happens the system cannot make pressure and the gear does not fully retract - it waits 15 secs and then the timer circuit pops the CB. We have tried bleeding the system and flight tested at max UC speed and steep attitude and the gear retracted within 6-7 seconds, so when its working it works well.
Beech tech support suggested the motor 60 amp cb may be at fault but when that cb pops the whole system is without power so the timer circuit does not work and does not pop the 2 amp cb.
My best guess is a sticking valve - maybe the selector shuttle valve - which bleeds pressure back to the return side, the trouble is figuring out which valve - thermal relief, pressure relief, selector shuttle, emergency hand pump??
RE: king air undercarriage problem
RE: king air undercarriage problem
It never fails on selecting UC down only on up, it always starts to retract and then stalls intermittently.
Good idea on the stethescope, the tricky part will be getting it to fail on the ground which it has not done yet - probably done 30-40 retractions at different times and its always been ok on the ground, which was why we did flight testing as mentioned before.
You mention expensive shotgun approach and I have found out that the powerpack has been changed 3 or 4 times in the last few years (before we got the aircraft), so I don't think this is a new fault I was really hoping someone else had seen it on a B300. Anyhow thanks for the input.
RE: king air undercarriage problem
Steven Fahey, CET
RE: king air undercarriage problem
Once again, god forbid that is the case, but it is worth investigating.
RE: king air undercarriage problem
RE: king air undercarriage problem
RE: king air undercarriage problem
that is it
Regards
Dave
RE: king air undercarriage problem
I´ve been working in a100 and be200 for a while. I recommend you, make a isolation check where the ground bonds are. Check the AC43-13B Electrical Systems provided by FAA. You will be surprised what you find.Good luck
FranAle
RE: king air undercarriage problem