Gear pins?

[Iz]

Just wondering, what is the use of gear pins?

I have asked many pilots and none have come up with a really good answer. Some say it's to prevent gear retraction on the ground. What happens though is that if you forget the little suckers, they prevent gear retraction in the air! Those things will get you in trouble if the preflight wasn't done 100%.

So let's have a shot at it! :)

[ft]

There are gear pins that will prevent accidental retraction of gear on the ground or during maintenance. The most common gear pins, however, deactivate the nose wheel hydraulics. If those were active, using a pushback rod would get rather interesting. Would the rod snap and go all over the place breaking handlers? When connecting or disconnecting the rod a pilot stretching his legs could make it flail about too, again breaking handlers. I would not have been amused if that had happened while I was working there. :)

Cheers,
/ft

[whisperer]

Just wondering, what is the use of gear pins?

The pins are there, as you suggested, to stop accidental retractions on the ground, this is kinda embaressing to say the least. As you mention they will get you in trouble if you dont do a good preflight, but not as much trouble as a wheels-up on the ground.
If you do misthem, simply land again and sort it out.

Used to be a fairly regular happening on the mighty Fin!

[Iz]

Thanks ft, didn't mean those pins though. The ground engineer takes care of that one, hopefully. I meant the ones that are in the retraction mechanism.

We have a ground interlock to prevent retraction on ground, don't we? I still don't see the advantages outweigh the possible disadvantages if you forget to take 'em out :)

[CargoRat2]

We use gear pins or a nose gear jack when loading very heavy cargo (50000Lbs+) through the nose door on the 74F. Saves the NLG tyres.

------------------
rgds Rat

[TwoDeadDogs]

Hi,Iz
Retraction on the ground is prevented by squat switchs and the flagged pins are a safety back-up.If you get the chance,have a look at the notice on the gear of an F50.It kinda grabs your attention.
regards
TDD

[HotDog]

On the CV-880 & CV-990 a warning light illuminated on the F/E annunciator panel if any gear pin was inserted. Pity Boeing and other manufacturers didn't follow this design, as I was caught out once with a 747F having been positioned on the ramp by maintenance with all main gear pins inserted without streamers on them. The last item on our after start checklist was all gear pins removed, which was confirmed by the departure engineer on the ground. After dumping 63 tons of fuel, we returned for a landing. The ground engineers said sorry but this incident still haunts me!

[Iz]

HotDog, aargh! I've heard similar stories and it's pretty embarrassing, even if it wasn't really your fault. That's what got me wondering about the pins.

2DD, I don't think I'll be in the vicinity of an F50 any time soon, can you give me the scoop?

[mcdhu]

When doing the walkround, look for the holes that the pins go in as well as for the pins/flags themselves. This has saved me from embarrassment on a couple of occasions when the flags had come off.

[HotDog]

mcdhu, you are absolutely right. Look for the holes and that is the philosophy I adopted on my walkarounds subsequent to my very expensive oversight.

[Le Pen]

Oh Puhleeeeeeease!!!!!!!!!!

I cant believe this thread..................

God, have any of you lot ever even SEEN an Aeroplane???????????

Sometimes I just want to weep! http://www.pprune.org/ubb/NonCGI/frown.gif

Anyway, lots of love

Le Pen

[Iz]

Le Pen, gosh I wish we all had your infinite wisdom. ;)

[HotDog]

LePen, I hope you were not one of the engineers who were supposed to have removed the gear pins after taxiing the airplane to the ramp?

[fly4fud]

Iz, all answers given here are correct :)
Just to more precise, the pins do indeed prevent the landing and take-off gear(s) to retract when on the ground. All the biggies have hydraulic systems, which when on, maintain the locking cylinders of the gear(s) pressurized (not talking about the extension/retraction cylinder here, those are , on most aircraft, pressureless once the cycle is done). So, no hydraulic pressure, and the gear "could" retract, e.g. during the towing of the aircraft or when subjected to strong (gales) winds. The pins then also prevents engineers (or pilots under instruction :) ...) from selecting the gear to up by mistake.

Thanks for reading my pinch of salt...

------------------
... cut my wings and I'll die ...

[spannersatcx]

Nothing is 100% foolproof and as such so as to prevent inadvertant retraction an/or collapsing of gear when being towed gear safety pins must be installed. We also have a SOP when if the a/c is on the ground more than X hrs we have to put the pins in (reasons as detailed by fly4fud).
Although on our checksheets there is always a statement to check for removal of gear pins etc, if they have been installed I(we) always make an entry in the log that they are fitted, so that until somebody removes then stows them and clears the log the a/c can't effectively fly.
Of course nobody ever misses them on their walkaround do they!
A/C have taken off with them still in before and it will happen again!

[Mr moto]

Some places, the groung crew will insist on the gear pins being in place before towing a powered down aircraft, for insurance reasons and that kind of thing.

[reboot]

Iz your who says you are a pilot, please tell me you only ever fly small aircraft with fixed gear. please please please I dont think I could sleep knowing you fly big a/c with retractable gear


:) :)
:) :)

[TwoDeadDogs]

Hi,Iz.
The F50 has a notice on the gear,warning people not to push up on a particular beam.Legend has it that after an F50 suffered a gear collapse,a Fokker training guy pushed up on said beam whilst demonstrating to new trainees.Sounds of collapsing aircraft and collapsing career.
The pins are put in for towing,to prevent a bump causing the squat switchs to activate the retraction circuit.
regards
TDD

[Iz]

Thanks a lot everybody! Appreciate the info.

Reboot, sorry to disappoint ya. Don't know why some people think I'm stupid for asking this. I've had discussions with various captains on this and many weren't sure either. So maybe they're stupid as well. Oh well.

I guess it would have been the most stupid if I walked around not knowing the facts and not willing to ask anyone.

[Cough]

A use that the engineers have for the gear pins is tracing a hyraulic leak in the retraction mechanism. If the leak is in the retraction lines, then these will not be pressurised until the aircraft is airborne, gear selected up, and the leak presents itself, albeit with no one present. So install gear pins, and select gear up. (Its nerve wracking!) The up lines are then pressurised, and you can then check for leaks.

Seen it done.

CCCCC......ough

[A and C]

Cough has hit on one of the main uses for the pins also on some aircraft when the hydrulic system is totaly de-pressuised to check the precharge PX in the accumulators this can miss position shuttle valves and when the system is re-pressuised strange things happen as the pressure gets into places it should not.

On the BAe 1-11 if you dont put the nose gear lock in after checking the stby steering acc px you run the risk of retracting the nose gear when the hydrulic pressure is re applyed.

[spannersatcx]

Of course we all know what happens when we don't fit the pins!
http://www.lae.mcmail.com/images/uc1.jpg
.
http://www.lae.mcmail.com/images/uc2.jpg

[spannerhead]

Looks to me like its sat on its ar$e.
Tail wheel colapse????

[maxmobil]

TwoDeadDogs,

>> Legend has it that after an F50 suffered a gear collapse,a Fokker training guy pushed up on said beam whilst demonstrating to new trainees <<

You are wrong in this point. It was an engineer who pushed up, saying "I don't believe the required forces should be so light".

NOW he believes, but has no chance to ever push the beam up again. The required forces are said to be just a few (around 5 ) kilopond.
By the way, also the first collapse has been due to improper handling of (another)engineer.

Two damaged F 50 within a few days, two fired engineers, has been a sad statistics for the maintenance at Vienna.

[bunyip]

Reminds me of a funny incident years ago. Airplane was a 748 and engineer did retraction tests in hangar then taxied airplane to line for me to fly. He came into the ramp (engineers could taxi under power there) taxiing fast and rough, and abruptly spun around and went back to hangar. I called and he said the nosewhel steering was inop, needed a new valve. None available, would be AOG.
Small island, and nothing came in for about 5 days, but then the airplane appeared on the ramp, serviceable for flight. I asked how he fixed it and he said he used an old valve that he repaired. (he lied of course)
Later I discovered he had left the gear handle up after the retract test on jacks, and when he taxied there was no pressure in the down line, where the steering gets it power.
If he had not had the pins fitted, we would not have had that airplane back for quite a while!

[poshed]

Spannersatcx

Is that a french classic?

exit door 5

[poshed]

Spannersatcx

is that a photo of a french classic?

exit door 5!!!

[spannersatcx]

Corse it is!

[poshed]

popular rumour has it that the crew were impressed that the stall warning worked!
Don't know if its true,nice story though