Cautious Belly
Registered Offender
- Joined
- Nov 28, 2005
- Posts
- 51
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Oops. Anyone know what happened?
Looks like nose gear skid marks. Does the 8 have nose gear brakes?
In PDX we were light and probably tail heavy, and as I recall we were cleared for an immediate with traffic on short final, so the nose was light enough that the tires didn't bite,................until I stomped the brake and the nose lowered. Then we shot back to the left and remained on the pavement. That one turned out to be a worn centering cam or some such crap. Plane spent a week on the ground and it was a MX nightmare to find the problem.
It's a hella ride!
Ground shift: Light aircraft, aft CG. When power's applied the nose comes up and the ground shift goes into air mode. This disables the tiller steering and does something else to the brakes through the anti-skid system. Any lateral drift is uncorrectable until either the nose comes down or sufficient speed results in the anti-skid giving the brakes back.
ABX have had a couple of 8s run off the side because of this - it's one of the not so nice characteristics - the moral being when light with aft CG to get lined up and not perform a rolling takeoff.
The rudder pedal control of the nosewheel is the only steering function affected by groundshift to the flight mode. The tiller still works until hydraulics are removed during retraction, and you can turn the nosewheel in flight with the gear down using the tiller (it's the first thing to try to raise the gear if you have trouble raising the gear). I'm with kaveman on our power application policy, and with heavyjet on being aligned with the runway when setting takeoff power at light weight and with an aft CG is a very good thing to do! (not saying the UPS crew wasn't...)
There's a valve that's mechanically operated by the physical extension of the nose wheel strut through the ground shift mechanism that shuts off the direct supply of system pressure to the steering, but as long as the gear itself is down, the same pressure that keeps the nose gear down is also supplied to the steering control valve. All the centering cam does is center the nose wheel when the strut is fully extended, and has no effect on hydraulics or ability to turn the nose wheel. First beer's on me if I'm wrong (and I may be!). You're right about moving the tiller if you can't raise the gear handle, which, if for some reason the strut didn't fully extend after liftoff may allow full extension and release the anti-retract latch.
I too could be wrong. It's been the better part of 10 yrs since I left the -8 for a more civilized ride, and I didn't take the time to dig the old manuals out of the basement and review the system. :laugh:
...and I didn't take the time to dig the old manuals out of the basement and review the system. :laugh:
OK, just don't pay attention to the other things I do in my basement:nuts::laugh:
It's probably all moot anyway. Just anxious to see what happened so it doesn't happen to any of the rest of us some day!
Moot indeed, as the tiller was working. I think we all agree that you can't stomp the brakes hard enough to skid the nose,...............although I'm sure they were trying.
I just hope they didn't dick up the plane too bad. It pains me to see another -8 gone. I got to land in Philly a few years back while an OOPS DC-8 was smoldering on the runway. Ya know,...............they ain't makin any more of them.