JT-8D From United States of America, joined Dec 2000, 423 posts, RR: 3 Reply 1, posted (11 years 3 months 1 day 19 hours ago) and read 2438 times:
If your talking about accidently retracting the gear, it should not be possible if the safety system is working correctly. On most airplanes, the gear handle is locked in the down position, if the weight is on the gear. It can be bypassed for maint purposes, but you better have the gear pins installed. If I didnt answer your question, post again..JT
JT-8D From United States of America, joined Dec 2000, 423 posts, RR: 3 Reply 3, posted (11 years 3 months 1 day 19 hours ago) and read 2404 times:
Im sure it has, but I cant remember a case that Ive seen myself. It is definetly possible though. Example, on 737, if you are going to replace the first officers fmc cdu, the gear handle has to be move to the "off" position. This will not retract the gear, but will not pressurize it to the down position either. What if you accidently move the handle through the off position, and into the up position? Just apply this simple rule--If you are going to move the handle, put the stinking gear pins in. It takes 2 minutes to install the pins, it could take weeks to fix the crushed nose of an airplane if you dont..JT
Metwrench From United States of America, joined Aug 2001, 750 posts, RR: 2 Reply 9, posted (11 years 3 months 1 day 15 hours ago) and read 2328 times:
Tech Rep can help with this one. Research a FACTS issue, about three years old regarding the Metro. I'll also look back, but this article, (News Letter issued by Fairchild) recapped two scenarios that caused nose gears to fold up on the ground. One of these cases caused a "Time Life" action to be created to limit the LDG control valve to have a Life Limit of 2500 hours, previously on condition.
As in any accident or incident, a long string of unfortunate events had to unfold before the misfortunes happened.
TechRep From , joined Dec 1969, posts, RR: Reply 11, posted (11 years 3 months 1 day 11 hours ago) and read 2324 times:
To answer your question it is very possible it could happen but yet very unlikely. Statically, with no hydraulic power applied, WOFW through whatever means and pull the gear handle to the retract position will have no effect. Now apply hydraulic power in the above scenario, depending on size/weight of the aircraft the main gear's will not tract but your nose will in most cases.
This is pure speculation of course but it can be easily tested even within the confines of most maintenance manuals. GEAR PINS INSTALLED, hydraulic power applied, lifting the gear handle will test all hydraulic carriers on the retract side for leaks and handle down all hydraulics on the extension side. Now in either scenario go out while your testing this and move the gear pins back and forth but do not remove them. You will find probably your able not to move the nose gear pin but the main gear pins you probably can.
I remember in the Air Force these fighter pilots would lift the gear handle just before rotation. So when the aircraft rotated, they would pull immediately into a vertical climb. I watched this on occasions and sure enough the nose gear would retract but mains stayed down.
The most important factor to this, is weight of course, the more weight and resistance acting against the retract actuator, the less likely it will happen.
NKP S2 From United States of America, joined Dec 1999, 1714 posts, RR: 6 Reply 14, posted (11 years 3 months 1 day 5 hours ago) and read 2250 times:
How've you been FDX? I hope all is well with you. Yeah, that was quite a situation at EWR wasn't it? A good reminder to never assume the last guy in the cockpit left everything in the cockpit configured correctly ( safely ). I'm sure glad I wasn't the one who turned the "B" pumps on. BTW: I still own the used 'Snap-On' roll-away I bought from the guy who DID throw the switch, when he left the company.
Bjones From United States of America, joined Feb 2002, 123 posts, RR: 0 Reply 15, posted (11 years 3 months 1 day 5 hours ago) and read 2239 times:
I don't know of any other examples but the Air Force primary jet trainer the T-37 actually has an emergency gear override button. If you hold that button down you can move the gear handle up regardless of weight on wheels. In training they tell you to use it as a last resort to avoid contact with something like a building or other aircraft in the event of brake failure. You can also use it in the air if for example the gear handle won't raise because of a faulty squat switch and you need to get the gear up to make it to an alternate due weather or something. They say only to use it in the air as last resort too because the problem causing the gear handle not to raise may cause gear to jam in up position as well.
Jet-a gasguy From United States of America, joined Dec 2000, 266 posts, RR: 2 Reply 17, posted (11 years 3 months 1 day 3 hours ago) and read 2210 times:
I watched a 757 gear's retract while the aircraft was on the ground.........of course the aircraft was on jackstands. Really fascinating to watch up close. That day at United's SFO maintenance facility was truly the highlight of my last trip.
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