UPS DC-8 in the mud @ GSO

[kaveman9]

That exact same thing happened to us just a couple of months ago in the -8 in PDX. No nosewheel steering through the rudder pedals. By the time you recognize it and transition to the tiller, you overcompensate and scrub the nose tire off. Take a look at the pavement on 10R in PDX. I think our nose skid is still there from October. Manual stomping of the left brake is the only thing that kept us on the pavement.

I've had it happen one other time many years ago, but it was actually some spring that snapped that caused the rudder pedal steering to go away. Screaming saved the day there. I was taking off, F/O. Moronic company policy dictates that the CA has the throttles even when the F/O is making the takeoff. Power came up and we were heading off into the bushes on the right. Full leff rudder had no effect. Full left brake slowed the divergence. Screaming got the CA's hand on the wheel(it was likely headed there anyway). Fortunately we had enough weight on the nose that the tires bit and pulled us back to the runway. Why the Co thinks it's better to have someone flying a 300,000# jet without complete control, I'll never understand. Sometimes you just don't have time to recognize what's wrong, decide on an action, verbalize those thoughts, and wait for someone else to react.

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!

 

[HeavyjetDC8]

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.

 

[b707guy]

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...)

 

[kaveman9]

The tiller steering was still working. That's how we got full deflection and the nosewheel skid. That's what shows in the pic of the OOPS plane above. Twice I've been aboard when rudder pedal steering was inop, and the obvious way to tell that is that during the rudder check you don't get feedback through the tiller. We had feedback through the tiller, both on taxi out and taxi in back to the ramp. That's what was so confusing about the whole thing. MX had a time figuring it out.

Even though we had the feedback, we didn't have much effectiveness. Tiller steering was normal, but on the taxi back to the ramp you could flat floor the left pedal and nothing. Flat floor the right pedal and the craft would slowly drift off to the right. Funny thing,.................MX changed the nose tires and said we were good to go. We agreed; we went to the hotel. I think it was eight or ten days later that the plane finally left the ramp.

 

[erichartmann]

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.

Light a/c, aft cg, the nose strut extends and drops onto the centering cam. This DOES disable the steering. Add to this one outboard slow to spool, and you will be in the tullies in a heart beat.

 

[erichartmann]

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...)

As I recall the extention of the nose strut engages the centering cam for the nose gear (which effectively disables the tiller) and puts the a/c in the "air" mode both electically and mechanically. Among other things it allows the gear to be retracted without pushing the "override" button. Turning the tiller if the gear handle cannot be moved before pressing the override button is an effort to dislodge the nose strut if it is not fully extended and allows the gear to be retracted normally.

 

[b707guy]

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.

 

[erichartmann]

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:

 

[hvydriver]

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:

707 guy is right.

 

[b707guy]

...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!

 

[erichartmann]

OK, just don't pay attention to the other things I do in my basement:nuts::laugh:

Heaven forfend!!! I have no desire at all to tread into TMI territory.:blush: :0 :beer:

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!

Amen!!!

 

[kaveman9]

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.

 

[b707guy]

Yeah, it was already leaving marks at what appears to be just past the 1000 foot markers (I know, they're just out of view in the picture) and way off the centerline, but I don't know offhand if there's a displaced threshold there for them to have built up a head of steam farther back. Sure happened quick either way. Waitaminnit - our folks didn't pull an old-style Kalitta and "borrow/trade" some nosewheel components from UPS at PDX to get ours fixed, did they?

 

[hvydriver]

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.

Speaking of UPS, talked to two buddies of mine over there. (One a maint. suit, the other a line dog) They both confirmed that they are still planning on scrapping the Diesels over there as they remove them from line service. That is I believe over 40 Diesels. Oh well.

 

[b707guy]

And, I believe, they (UPS) own all the STCs for our beloved Douglas beauties. If so, then once they stop flying theirs, the rest of us are SOL for support. How many does Astar have now? APC shows only 8.