Is a Nose Gear Lock Pin necessary on pushback?
Joined: May 2001
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From: Mumbai, INDIA
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
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
Joined: Aug 2003
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From: At work
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.
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.
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From: deco stop
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
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
Thread Starter
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From: Timbuktu
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.
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.
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From: West Country
Originally Posted by maxalt
FWIW, we use them, and nobody has had one left in after push-back for at least the last 20 years.
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.
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From: The Sandpit
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.
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.
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From: Stockholm Sweden
Originally Posted by Jet II
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.
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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.
Thread Starter
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From: Timbuktu
Err Max, I thought you flew for us?
As I suspected though - seems very few are using the NLG lock pin nowadays.
Anybody from Emirates here? Whats YOUR company SOP on this?
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From: Somewhere between MSL and the Stratosphere
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.
Also some airlines have a legal requirment for the Captain to positively see and identify the three pins 'fore commencing taxy.Cheers anyays.
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From: Balmullo,Scotland
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.
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From: HAMPSHIRE
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?
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?
Joined: Aug 2005
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From: HAMPSHIRE
RESPECT
Originally Posted by matkat
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.
THERE IS ALWAYS A REASON WHY (SAFETY)
IF IT IS DIFFICULTTO PULL THERE IS NORMALLY A PROBLEM?
STIFF MEANS UNSAFE???????????????????FORGETFULL MEANS COMPLACENCY????????????????????????
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From: Balmullo,Scotland
Originally Posted by Rusty443
THERE IS ALWAYS A REASON WHY (SAFETY)
IF IT IS DIFFICULTTO PULL THERE IS NORMALLY A PROBLEM?
STIFF MEANS UNSAFE???????????????????
FORGETFULL MEANS COMPLACENCY????????????????????????
IF IT IS DIFFICULTTO PULL THERE IS NORMALLY A PROBLEM?
STIFF MEANS UNSAFE???????????????????FORGETFULL MEANS COMPLACENCY????????????????????????
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?