Is a Nose Gear Lock Pin necessary on pushback?
 

Bit of a debate here about the necessity of a NLG lock-pin for pushbacks.

Does your company use them - and if not, why not?

L10, not required, nor necessarily desired.
One more thing for the ground crew to forget...:ugh:

If L/G System is Pressurised Hydraulically.The Disconnect Pin Isolates the Pressure & return lines to the Steering Actuators & helps create a runaround between the Actuators to enable the NLG to move freely with the Tow Bar.
Engines can be started on Pushback saving Vital time.
The Steering pin with Red streamer is removed after the Tow bar is disconnected & shown to the Pilot at Taxi clearence by Ground crew.

regds
MEL

Hawk21m I think you are talking about the nose gear steering bypass pin as opposed to normal gear lock pins in general.

We do not use lock pins for push back nor do I see the need for them. The gear would have been designed not to require the pin installed for pushback. Also the pins are stored in the flight deck so lgistical issues about returning them remain, unless the tug has a whole bunch of spares.

You are correct.I was referring to the Steering Disconnect pin.
Te LG lock pins are not used during Pushback during Normal ops,However We do use them during Mx Pushback/Towing ops.
regds
MEL

any answer for corporate types
 

this is also discussed by us, on a regular basis.

it is suggested that on push back and on a tow, from stand to deice, 9for example), ALL three pins should be in.

So my question is: on a Gulfstream 5/550, is it required to have the main gear pins in, for either function, and/or is it necessary for the nose pin to be in.

Assuming that the hydraulic pressures are being suppoerted.

windy

Its the LOCK PIN I'm referring to here - not the steering disconnect pin.

OK, I'll rephrase the question.
On my Airbus the nose gear LOCK pin acts to prevent undesired movement of the the over-centre lock actuator mechanism.
The over-centre mechanism keeps the gear mechanically locked down. If this over-centre mechanism were to fail during (for example) emergency braking by the tug on pushback - would it result in a gear collapse?

Some say NO - you would have to operate the gear handle to (hydraulically) operate the actuator which breaks the down lock before you could get a retraction, and nobody is likely to do THAT. Hence you don't need a pin.

Others say YES - if you had a hydraulic failure to the actuator coupled with a sudden stop by the tug, it would be possible for the over-centre to break and allow gear collapse.

Having a pin in may be belt and braces - depending on your point of view above - but the only drawback I can see in having it in is that (as 411A said) somebody might forget to remove it some day.

FWIW, we use them, and nobody has had one left in after push-back for at least the last 20 years.

Who do you work for - in over 20 years in the industry I have never known any major airline insist on fitting ground lock pins for pushback.

In fact the ground-pins are kept on the aircraft and there has been a continued effort to stop people using 'spare' ground pins that cannot be controlled as they tend to get left in - turnbacks due to pins left in and gear retraction failure are not unkown.

Err Max, I thought you flew for us? We don't use a nose gear lock pin for pushback! certainly not here at LGW.:=

The whole point of the mechanism is that it is over-centre. In order to break, it has to go through the centre, inline position so that it can pivot in the normal way and therefore allow the gear to retract. Any pressure on it will tend to increase the over-centre pushing against the lock stops in the opposite direction to that which is required to retract the gear.

I have had to manually break the lock to retract the gear in order to allow a nose leg seal change. It takes a 5 foot bar and a good heft to get the lock back through overcentre to allow the gear to retract with no hydraulics applied and I'm 6'3" and 100 Kgs. :eek:

There was a time from about 1979-86 ish when it was a required procedure on the Tristar. There was a failure mode of the undercarriage selector mechanism which retracted the gear with hyds on and an AC power failure. In all that time we used NLG lock pins for push back. We had special ones made with long metal sticks on them so they could be easily removed after pushback. Since then I have never used them on pushback. The hydraulics are pressurised and the pin is redundant. It would need the failure of two big springs, and the hydraulics, and the tug to give a push.
When towing aircraft unpowered, we use a NLG pin only. Some airlines here use all the gear pins, but our airline does not require it, and I agree with this. NLG usually retracts forwards, which means the tyres roll across the tarmac. MLG retracts sideways so the tyres have to scrub across the tarmac.

Whaddya mean 'us' Keemosabi?

As I suspected though - seems very few are using the NLG lock pin nowadays.

Anybody from Emirates here? Whats YOUR company SOP on this?

I believe BA pushed a TriStar (many years ago) minus the NLG downlock pin & had a coming together of the aircraft & the tug.

Nope.Never used one of those in EK either.Neither in my previous company on NGs.It sure would be a bad day if your over centre locks were to fail AND your hydraulics were to fail AND you got yourself the worst tug driver in the shift,who THEN decides to do a sudden stop!!! Which is exactly why they have been rendered redundant.Besides ofcourse the logistics involved in keeping a "spare" set in the tug.Which is exactly how the problem started to begin with!
Also some airlines have a legal requirment for the Captain to positively see and identify the three pins 'fore commencing taxy.Cheers anyays.

Swedish Steve is indeed correct about the TriStar, and this specific selector valve condition was corrected by manufacturer service bulletin quite a long time ago.

Any current EMB-145 drivers care to comment on the Steering Disconnect PB?

As a line Engineer I never once used a nose gear pin for push back simply it is very difficult to get out(B747s) and it is also easy to forget, anytime We had them in for maintenance a log book entry would always be made to this effect.Nose gear steering by pass pins were of course always fitted(or whatever was used to isolate/disconnect nose wheel stearing) and removed on finish of push back.

Reasons
 

I would like to comment from the rampie side, boys and girls!

First there is three ways of depressurisation,

1: CB
2: PIN
3: DISCONNECT THE TORQUE LINK

As for gear locks this refers to a/c types such as MD83 or SAAB 340 /2000 Etc.

Remember safety is the importance and a/c differs with type?

Also different Airlines and aircraft specify different rules.

No HYD can cause a nose wheel to fail, these rules are written into ramp manuals for safety it will never happen?

SO WHY IS IT WRITTEN?

RESPECT
 

THERE IS ALWAYS A REASON WHY (SAFETY)

IF IT IS DIFFICULTTO PULL THERE IS NORMALLY A PROBLEM?

:= STIFF MEANS UNSAFE???????????????????

FORGETFULL MEANS COMPLACENCY????????????????????????

Rusty I guess You have never heard of Murphys law then? complacency is removed from the equation by means of the log book entry I never said it was stiff to remove I said difficult so again I presume You have never worked 747s
as I said I have never been required to fit a gear nose pin, must be a good reason why not! and if it was required why not go the whole hog and fit pins to all the gear whilst pushback wonder how many turn back would occur then?

If steering bypass pin on steering actuator of nose landing gear is not installed on B737NG then sys A hyd. pumps(both) should be off and alternate steering not selected(sys B).:ugh: