View Full Version : Importance of seeing the pin
AnthonyGA
4th Oct 2007, 15:50
Why is it so important that the pilots see the ground crew holding the pin at pushback? Is it a potential safety issue or is it just to avoid extremely expensive damage to the aircraft? What happens if someone forgets to remove the pin?
Rainboe
4th Oct 2007, 16:04
This is not the pin that locks the undercarriage from retracting (damn things!- terribly embarrassing to take off with one in........so I'm told). Those are only attached to each leg by engineering overnight to lock the gear down, and are checked removed before first flight and placed on the flight deck. When a pushback tug is attached to the nosewheel, a different pin is inserted in the leg to lock out the nosewheel steering. As the pushback commences and the engines are started and the hydraulics fully pressurised, you do not want the nosewheel to turn and break the tow bar, and possibly damage or break the pushback crew. Once push complete, towbar disengaged, the pushback crew will remove the pin to activate nosewheel steering, and walk away to show clear of obstructions, and hold up the pin so the pilot knows he has nosewheel steering. Forget to remove the pin and the steering tiller won't move. No steering possible at all.
All very pedantic and precise, but must be followed to the letter. Sometimes pushes commence before brakes have been released (removes leg), and tugs detached without brakes applied again (causes lots of shouting and arm waving). People have attempted to taxi with tug still attached, with the pushback crew still attached by headset (if you get airborne with them there, they do tend to bang against the fuselage a bit, until the cable breaks, and require replacing). More can be bred though- there seems to be a steady supply.
North Stand Tier3
4th Oct 2007, 16:38
All as the man Rainboe said! One exception is the Embraer 145 which has a flight deck circuit breaker to isolate the steering with no de-activation on the nose gear. Obviously don't trust the pushback crews in Brazil
Right,I'll get me coat...........................
perkin
4th Oct 2007, 17:10
I was on a KLM flight ex-LHR fairly recently when the pilots only realised the nose-gear pin hadn't been removed by the ground crew when they tried to taxi away from the position they had just been pushed back to and realised they had no steering...
I seem to recall the flight was delayed a bit so this is perhaps an example of what can get forgotten when under pressure to meet a slot time...As the groundcrew's headset had been detached, I'm guessing some frantic waving was involved!!
Is this item on a checklist at all (737NG in this instance), or is it just procedure that the ground crew present the removed pin to the flight crew?
Rainboe
4th Oct 2007, 17:54
No checklist. You just have to accept it is one of the procedures you must carry out from experience and not rush in any way. It's easy to miss a step. You must tell the pushback crew to disengage, they say goodbye, you wait for their wave and see the pin. That means you are now unobstructed for taxi.
perkin
4th Oct 2007, 19:05
Thanks Rainboe, I wasn't sure if it was perhaps on some post pushback checklist if such a thing even exists! I do think it was a little bit sloppy all round, neither ground or flight crew questioned the lack of pin until the aircraft was moving, but I guess these things can happen when there is such pressure on slot times and the like and of course it could've been a much much worse oversight...!
Actually it is a check list item in Rainboe's airline:uhoh:
(Part B:2-1-74 for the next line check:))
perkin
4th Oct 2007, 20:35
You don't work for a Dutch airline by any chance do you Rainboe? ;)
Rainboe
4th Oct 2007, 22:49
Well it's only one little entry, just to say the whole caboodle is completed. But to do the caboodle, you have to do it all from memory. Years ago had big language problems (blame the French) with the pushback crew. He said something and I said I do not understand, please repeat. I had the sudden feeling just hearing a reply from me was enough for him. I released the brakes rapidly just as there was a powerful lurch backwards, like a very hard clutch being released in a car, as they started the push anyway. Doing that sort of thing with the brake on actually collapses the nose leg as the bar attaches low down. Pushbacks are one of the most incident-prone times.
brain fade
8th Oct 2007, 00:52
You need to see the pin, so you KNOW the pin is not in the gear.
Wave it- show it. It's not the pushback crews responsibility to take it oot. The Captain needs to make sure it's out. (He will get the blame if it's not)
Therefore the pushback Engineers waves it to the Captain- who sees it, and waves back.
Rainboe
8th Oct 2007, 08:49
It is not the Landing Gear Locking pin that stops the gear being raised that is shown. The pin shown is the Nosegear Steering Lockout pin which prevents any nosewheel steering at all.
It's not the pushback crews responsibility to take it oot.
Got to disagree there.
It is their responsibility to remove it and show it to the flt crew.
It is also the responsibility of the flt crew to check that it has been removed, usually by seeing it in the hands of ground crew but also verifying through other methods, whether that be verbal, or ECAM/EICAS message on the flt deck instruments.
Taking time to check may take a few seconds extra, rushing tends to get people hurt. :ok:
brain fade
8th Oct 2007, 11:56
turin
You're right of course. what I was trying to say was that while it IS the pushback guys job to take it out, it's the Captain who carries the can if it's left in, not the engineer.
North Stand Tier3
8th Oct 2007, 19:42
Unfortunately the engineer is usually necking tea when an a/c pushes back nowadays-joys of costcutting I'm afraid
Right,I'll get me coat...........................
AnthonyGA
8th Oct 2007, 22:42
"Necking tea"?
Rainboe
9th Oct 2007, 00:18
Pouring tea, down neck. You French should try it, then you'd understand what Britain was built on. But you insist on doing the coffee thing, and 'Kronenbourg 1667', and smoking those appalling cigarettes that must be killing you, and eating weird parts of geese with great relish. We must change you. It's for your own good. You will be assimilated.
If the Nosegear Steering Lockout Pin prevents any nosegear steering, how does the tug turn the aircraft?
Just curious.
The pin simply stops hydraulic power being applied to the steering collar, it does not physically lock the gear from turning :)
Rainboe
9th Oct 2007, 12:11
I wasn't clear. It prevents any hydraulic steering input from the pilot. The pilot tiller will not move, but the nosewheel steering will castor happily as the tug pushes, pulls and turns.
North Stand Tier3
9th Oct 2007, 12:56
Varies from a/c to a/c. 737 Classics and other museum pieces have cable input and feedback so the tiller will move but most modern types use 1s and 0s or potentiometers to steer so no feedback when isolated.Give me the thicker wiring and a tensiometer anyday......
NATO standard -white,two sugars- by the way...................
Brain fade: the pushback guys are very rarely "engineers".
If you're gonna lump us in with baggage handlers, then why not get them to assess the dent, next time one of them smacks your airframe.