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737-200 Nosegear Incident

Sat Feb 24, 2001 12:58 pm

I'd appreciate responses from any who are familiar with 737-200 nosegear that would enlighten me about this one.

Aloha #92 (N804AL; a 737-200 with "plenty" of "doublers" on the fuselage skin) pushed out of Honolulu gate 53 on 2/22/01 - destination: Kona.

The pushback lined us up perfectly with the intended initial taxi.

Initial taxi was perfectly straight from stop, and we attained moderate speed after about 20 seconds.

Suddenly, a loud CLUNK from the nose.

Pilot S L A M S on the brakes, and we STOP RIGHT AWAY.

Many passengers react - "we hit something."

Stew comes on, "Please stay seated until we hear from the cockpit."

Captain comes on and says, "We had no steering control, so we stopped. A mechanic is coming out."

Engines still running.

Mechanic comes out in a golfcart. Spends 3 minutes at the nosegear, and drives away.

We resume our taxi and take off uneventfully.

My hunch is that one of the ramp guys might have, "neglected to do something."

The pilot didn't realize he had no steering authority until he tried to deviate from the initial straight line taxi.

Again, any help would be appreciated.









 
NKP S2
Posts: 1665
Joined: Mon Dec 20, 1999 3:16 am

RE: 737-200 Nosegear Incident

Sat Feb 24, 2001 1:39 pm

The nosewheel steering bypass pin was not removed before the wave-off. The clincher is that you said the pushback lined you perfectly with the intended ( initial ) taxi out. Years ago on the 737 they just made certain the "A" system pumps were off for pushback...as pressure will try to center the gear during pushback. Newer 737's have, and older 737's were retrofitted with, a bypass valve in the pressure/return lines, located on the upper R/H part of the gear: This valve is pushed in by hand and held in bypass position with a small clevis pin. When in bypass the nosewheel steering system is not pressurized even though the "A" system is pressurized...although it is common practice for some operators to have the hydraulic pumps turned off as an added margin of safety...per checklist. FWIW, most A/C have a similar system to deactivate NW steering...either mechanically with a lever/plunger and pin or a switch in the cockpit or on the exterior. BTW, not all that rare for events like that to happen Smile
 
AV8N2
Posts: 39
Joined: Mon Feb 26, 2001 10:08 am

RE: 737-200 Nosegear Incident

Tue Feb 27, 2001 2:29 pm

NKP hit the nail on the head there! Most (or I should say many) of the 200s are converted now to have the bypass pin removed. The 300+ have a little different set up, ie no pin.
The Bang you heard was just the pin shearing, no harm to the ac itself!  Smile
BTW, probably was a maintenance personell error, but either pilot should have caught it.
 
cdfmxtech
Posts: 1319
Joined: Wed Jul 05, 2000 11:37 am

RE: 737-200 Nosegear Incident

Tue Feb 27, 2001 3:56 pm

AV8N2

What -300s do you fly, because every-300 I've worked on has the steering depressurization valve (push in and insert bypass pin).
 
AV8N2
Posts: 39
Joined: Mon Feb 26, 2001 10:08 am

RE: 737-200 Nosegear Incident

Wed Feb 28, 2001 1:02 pm

CD...
Actually, I have never flown the 300. I just assumed that the 400 had the same gear...my mistake! The 200s that I fly have all been recently converted to remove the external pin, yes. The 400s never had the provision for a bypass pin, as far as I am aware of.
 Smile
But hey, I just fly em!!!