Something that came to mind recently. How do you guys take into consideration the FOD that is not preventable. Sand, dust and fine dirt etc. Is the maintenance schedule modified depending on where you operate your engine? What is some of the more dangerous and unpreventable matter that our engines can ingest? Is this something to even talk about or am I just thinking too hard? [sm=what_smile.gif]

Thanks! Pete

besides using a Tam FOD screen I fly exclusively off concrete and won't fly off grass/dirt. I've had a few grains of sand be ingested that scratched the compressor but every one I've had in for service this has never been an issue and I've never had bearing problems.

Yeah, concrete is best for me too. I havnt flown off grass yet. But I am VERY careful to not leave any fod in the interior of the jet. I always use a fod screen, and checking for fod is part of the pre-flight. I have intake and exhaust covers as well when not flying. Just 1 teeny nut or pebble can be a costly misfortune.

What we have found from flying helies, is that flying off of pavement of any kind is going to sand blast the heli and wipe out the bearings pretty quick. No how much you sweep there is always abrasive dust on pavement.
The cleanest surface to fly from is lush green grass.

that's not the case at either of the fields i fly at, one is 300x1500 concrete and the other is 900x2500 concrete, i've been flying heli's sense early 1990 exclusivily off concrete and i've never had bearing problems. our concrete is 'swept' 18hrs/day 5 days/week by Blackhawks and D model 58s and there is very little sand/grit on the runways.

May be thinking too hard. I have several thousand flights off the dry lakebeds in California. Lots of dust, dirt and tiny grains to small rocks plus a lot of wind to stir it up. FOD guard catches the big stuff and the rest doesn't do anything except polish the blades and fill up the nooks and cranny's (per John Redman when he worked at Jetcat). Even flown thru dust caused by my own takeoffs and thru blowing sand.

Of course, if you don't use a FOD screen you take your chances. Otherwise, I lost any concern for it years ago. Many of us fly in this environment without any real issues. Plus dozens of guys come out to test fly their jets there.

One of my P-70's did 100 hours without service off the lakebeds and both it and a P-80 are now each over 200 hours. That's over 2,700 flights & 420+ hours between them out in the dirt. They and my other engines have obviously had servicing, but not normally due to the dirt.

I fly in the desert.
Lots of sand...



One of the local guys have a 5 year old P-80 with 100 hours on the clock. It had never been to serviced since recently.
I sent the engine to Jetcat Germany for a major overhaul about 2 weeks ago.
They changed the bearings and said that they were old but still serviceable...
I send all my engines to Jetcat for servicing on the standard schedule. Nothing special if found.

So basically same feedback as Thud Driver.
Don't worry too much about the small abrasive particles that go through the FOD screen.

Some lovely camel sh... that makes a great effect when stuck on a FOD screen.

It's worth it for the sun you get out there!
Talking fods, my new P-80 makes a whirring noise on initial spool up (electric) if I waggle the fod gaurd a bit it goes away. Ali made a comment that I will knacker the o ring/start motor. It appears to be caused by the main fuel feed putting a little tension on the flexible motor mount as I have made it a close fit. Is this normal or should I open the hole in the mesh a bit to relieve it? Gary.

Well I'd say that the whirring noise is a sign that the clutch is not perfectly centered on the cone isn't it ?
So Ali is right in his assessment ( as usual ). Try to get the noise out by opening up the hole. Then you can "reform" the mesh at the correct position and glue it with thin CA.

Kinda dry and hot out that way in the desert. I would guess that at high noon you are looking for a nice shade tree. I have a friend in Agadez. Do you know where that is?

MACE

Thanks for that, I'm sure you are right, if I open the hole a little too much I can always put a dab of silicon round it I guess. It doesn't seem to take much to disalign the clutch motor does it? Pity JC don't use three arms on the motor support.