Forum: F-16 Procedures

Hello, I'd like to know why we install the NLGGSP after the engine shutdown. Also I'd like to know if there is any country that has its own regulations about this, I mean, doing the contrary.

Thanks!!!

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Jinx, how are things in lovely Iquque? I was there for a site survey in April '02, great country, great people. To answer your nose gear pin question- it's a safety issue,not real smart getting that close to the intake while the engine is running. Have a Pisco for me, Chow

It is a safety issue alright...but not for intake proximity. It's got something to do with loss of hydraulic pressure after shutdown. Without pressure, the down lock mechanism for the nose gear and the main gear collapse under the weight of the jet, which can ruin an otherwise perfect sortie. Doh

....at least, I think that's how it works.

Oh, so why is it ok to get in the wheel well then?

Jinx wrote:

I´d like to know why we install the NLGGSP after the engine shutdown

falconloader wrote:

Oh, so why is it ok to get in the wheel well then?

If you're stowing the pin and that's where it's stowed then that's where ya gotta go. But he's not talkin' about stowing it, but installing it. Hence my answer.

LinkF16SimDude wrote:

It is a safety issue alright...but not for intake proximity. It's got something to do with loss of hydraulic pressure after shutdown. Without pressure, the down lock mechanism for the nose gear and the main gear collapse under the weight of the jet, which can ruin an otherwise perfect sortie. Doh

....at least, I think that's how it works.

Not true, if that was the case you could not walk out to every aircraft on the flight line and pull all 3 pins without the gear collapsing, but you can. Pins are not there to keep the gear from collapsing thats the downlock's job, the pins are there to prevent an idadvertant retraction of the gear. I was taught installation of nose gear pin was an intake poximity question but that may be wrong.

Pete

LinkSim, you have to get into the wheel well to retrieve all the pins, why would the nose wheel pin be any different from the rest of them? Normally all pins are installed before crewchief gives the ok for the pilot to shut down, so personell will be finished pinning nosewheel, maingear, tailhook,epu,fueltanks, and whatever else needs to be pinned. Hence, i don't think hydralic failure is the reason why you don't pin the nose gear until after shutdown, but hey if you can reference that, i'm all about learning.

Hydraulic failure has nothing to do with the gear at that point. The downlock actuators in each drag brace are spring loaded to the "extend" position, locking the gear down. A hydro fail would actually further safe the gear making it impossible to retract. Evil or Very Mad

In the USAF the nose gear pin is installed after shutdown for one reason and one reason only, Hazard Area due to intake suction. It is a hazard area for personnel as well as possible damage to the engine from the pin being ingested. A prime example of this actually happening was the F-22 that ingested the nose gear safety pin right from the hand of the crew chief who was attempting to install it.

OK OK....I was wrong and I'll take my hits.

Quote:

The downlock actuators in each drag brace are spring loaded to the "extend" position, locking the gear down. A hydro fail would actually further safe the gear making it impossible to retract.

So if the gear stay locked down even with the pins out, then why have pins at all? Confused

Gotta be a reason. Would ya need 'em for when the jet's being towed perhaps?

Reasons for pins
1. Towing
2. Prevent inadvertent gear retraction while Hyd pressure is present (inadvertent retraction requires various combinations of WOW switch/Downlock Release button failure and gear handle accidentally positioned up)
3. Prevent gear retraction when handle is purposely placed up with hyd pressure present with aircraft on the ground (brake ops check)

Cant really think of any other reasons

Pete

The are several pics on the site of the AZ and HL jets that had gear retractions on the ground for the exact reasons that Pete stated. Not following the TO is kinda hard to explain......

http://www.f-16.net/gallery_item15763.html
http://www.f-16.net/gallery_item15803.html
http://www.f-16.net/gallery_item15807.html

I was in the AZ unit when that happened. What a trip to see the jet like that.

Pete

We had the same rule in the RNlAF ever since a NLG pin was sucked into the air intake. This happened because a crew member did not hold the pin properly and the streamer caught the sucktion of the intake and off it went, damaging the engine.

All our aircraft were modified to prevent a gear collapse after shut down and the procedures changed to install the NLG pin after shut down. We also pulled this pin just before engine start for exactly the same reason.

Cheers, Berry

A long time ago we would check the nose tire on initial chocking and tire check. Once a weapons troop did this and was killed from injestion we were told to stay out of the area while the engine is running. The main gear is currently pinned after engine shut-down per the cards for whatever reason. I'd like to know the history of this decision because, again a long time ago, there were issues with the gear collapsing when the generator went off line and we had to watch for movement at shutdown. I know the mods were put in place but you never know what else might go wrong.

Forum: F-16 Procedures

Nose Landing Gear Ground Safety Pin regulations