Re: Undercarriage retraction on the ground

From:         Paul Kearney <>
Organization: Ireland On-Line
Date:         12 Oct 96 21:34:30 
References:   1 2 3 4
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> >At flight test, they put locking pins in the retraction mechanism after
> >landing and before towing.
>    To follow up a note I sent earlier,  I found someone who knew more
> about gear pins, who said that the airlines consistently remove the gear
> pins the first thing after delivery and toss them.  The lock mechanisms are
> overcenter backed by beefy springs, so something drastic must have been
> done wrong.
Pins are not thrown away , they cost alot of money to replace !

Pins are required for towing/not-in-use time/during hangar visits.

On 747 the Nose wheel pin is normally on the end of a bar about 5 feet long.

This bar+pin plus the steering locking pin are withdrawn during pushback
and are the items you will see the push-back-engineer holding up to
the aircrew as part of the see-out procedure.

During hangar vists the pins are the first things to be put in
to inhibit gear movement and when theyre removed for function checks
the personnel around the aircraft are made aware of this for safety

In real life , if an aicraft is pushed back with steering lock pin in
place then the push/tow-bar should break first.

For a nose-wheel to collapse something physically went wrong.

And who ever was in the cockpit when it happened would have been brought
out of the collapsed aircraft as if he/she'd just seen a ghost ( or two )

Regards to all