Home Forums Hunting & Shooting Hunter's Campfire Turbine A&P mechanics help needed. I’m asking everybody I know.

I met a former Lear engineer who presented at the IA seminar a couple years who might help. Will look for info and pm if I find him.

Thank you all, I am following all responses and I am appreciative of all of them.

Just to clarify, I am 100% confident there is no bleed air leak. After several through extensive inspections, nothing is burning in there.

The red EICAS message can’t be ignored. The checklist to make the light extinguish is followed and the flight can be completed as planned.

I will follow the advise given. If it is some sort of AV glitch, I want it fixed. Damn computers!

Thanks again to everybody.

Try contacting these people. They know Lear jets.

https://airaffairs.com.au/

Remember the good old days when all you had to worry about was a fire warning light in the engine "T" handle...

Don't get me started on fire warning faults and T Handles....

FL420 is way up there a cracked exhaust flange might give a fault up high and be hard to find on the ground. I assume the mechanics used soapy water on a running engine before they said there were no leaks.

Some aircraft, Piper Cheyenne III comes to mind can have a bleed air leak with no indication.

When you pull the power back you are reseting something. As someone said earlier these is a PC board somewhere with corrosion on the puns or a leaky diode or a faulty transistor.

You need to isolate the airframe and engine seals and tubing first as that is the easiest

As you know a bleed air leak can cause a lot of damage in a hurry.

Fire loops can be such a pia to troubleshoot at times but it's possible that the connector that leads up to the loop is breaking down when it gets warm. I'm not so sure it's an avionics issue since it turns off when you shut off the rt bleed air and idle back the engine, has it been checked on a ground run or is that even possible? I've only ever worked on heavies so I'm not schooled up on these particular airframes.

Is there a change in the pressurization or air conditioning schedule at around 40,000’ ?

Talking about this over coffee with ATP pulled up.
A friend said he has seen insulators on the fire loop ground out an hour into flight . Airflow, pressure and temperature change caused it.

Some baling wire and duct tape and you'll be good to go.

Does it happen if you level off below FL430????

I can't believe ALL your flights you go to 43.....

Can't really believe that with both warnings in RED and on multiple occasions that the plane hasn't been grounded, if not by the owner, then by the pilot...

Phil

Is this aircraft an LJ-31A?

My BIL spent 23 years in the AF as a jet engine mechanic, got out and did 20 something with Honeywell. Anyway this is what he says. Probably a bad over temperature sending unit...seen this before when I was in the AF. That's a pathetic A&P mechanic if he can't figure that out. They will get a computer disagree code for it eventually. Mechanics these days don't know how to troubleshoot a problem, they need a computer to diagnose for them.

My brother’s an A&P.

Get a new A&P.

Ask your A&P to clean the computer ground connections at the airframe and the terminals. It is amazing that how many glitches like this are caused by nothing more than a poor ground connection.

drover

This sounds likely. I have a bit of GE and Allison experience, and bleed air isn't an uncommon problem. The fact that it comes in after leveling off is key. Could be temperature related, and could be the harness is being affected by the change in flaps. Chase grounds, cannon plugs, and the sensor first.

Is it calculated or measured?

I still don't know whether this is a 31A or not, but if it is there are two temp sensors associated with bleed air: one for the bleed air duct and one that senses temps in the pylon. When you say "fire loop," I think of the fire loops inside the engine nacelles for detecting engine fires. I would imagine that this is a common configuration on the Lear business jets (admittedly a shot-in-the-dark guess).

This is the obvious answer. Also, I wouldn't run it with the red light on. It ain't rocket science.

Yes. Bleed air comes off before combustion.

No, not all flight are to 410 or 430, but I’ve never had it happen yet at 430-450. Yesterday it didn’t happen at all and I flew for 3 hours above 400. If I stay below say, somewhere around 320, I haven’t seen it. It seems to happen right around the 400 level.