P-38 Incident (no injuries)

[Robbie Stuart]

IDENTIFICATION
Regis#: 79123 Make/Model: P38 Description: P-38, F-5 Lightning (L-222/322/422)
Date: 06/06/2009 Time: 1800

Event Type: Incident Highest Injury: None Mid Air: N Missing: N
Damage: Minor

LOCATION
City: FAIRMONT State: NE Country: US

DESCRIPTION
AIRCRAFT DURING TAKEOFF AT AN AIRSHOW, BLEW OUT A TIRE, FAIRMONT, NE

INJURY DATA Total Fatal: 0
# Crew: 1 Fat: 0 Ser: 0 Min: 0 Unk:
# Pass: 0 Fat: 0 Ser: 0 Min: 0 Unk:
# Grnd: Fat: 0 Ser: 0 Min: 0 Unk:

WEATHER: VFR

OTHER DATA
Activity: Unknown Phase: Take-off Operation: OTHER


FAA FSDO: LINCOLN, NE (CE09) Entry date: 06/10/2009

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[Holedigger]

At least no one was hurt. Did they get airborne or abort? How available are P-38 tires (or tyres )

[Holedigger]

Reg # would make her Rough Stuff?
http://www.warbirdregistry.org/p38regis ... 27231.html

[Matt Gunsch]

Tires are out there, but expensive. they use the same tire as the nose wheel on the A-26,

[Holedigger]

How big a problem is that getting to be with these older FLYING warbirds? It really is a big safety issue as well as a cost issue. If getting "new" tires are being put off until they really need to be replaced, that is a problem! Small batch production "boutique" tires is an expensive thing as the market is so small. I read that our local Starfighters demo team is babying their supply of tires because of cost and short supply.

[Ztex]

Glad to hear that it was not serious.

Years ago the B-17 Co-op got together to make a quantity main gear tire purchase.

Have other owners banded together like that to make things a bit cheaper?

How big a problem is that getting to be with these older FLYING warbirds? It really is a big safety issue as well as a cost issue. If getting "new" tires are being put off until they really need to be replaced, that is a problem! Small batch production "boutique" tires is an expensive thing as the market is so small. I read that our local Starfighters demo team is babying their supply of tires because of cost and short supply.

I wouldn't start jumping to conclusions. There's a dozen reasons tires blow out besides from being worn. Could have run over some FOD, or had a brake problem, sliced off a valve stem... I doubt very much that the airplane was flying around on bagged-out tires. The Stearman Restorers Association was recently able to get someone to make new production 10.00 SC tailwheel tires after the old molds were accidentally scrapped some years ago. They're Chinese, but a little work removes the obvious evidence.

[Matt Gunsch]

there was a limited run of the tires several years ago, and those that have them, are using them carefully. We had a hard time finding one to use on the A-26.

[kmiles]

There was recently (last summer) a batch of 36 SC tires done. We use them on the nose of the B-24, and that is the same tire that is used on the main gear of the P-38. The tube used in the tire is more difficult to find than the tire, and the "new order" of them has not been finished yet. If they had a tube issue (usually the case), hopefully they have a spare.

The B-17 co-op put together another order of "new" tires 2 years ago, so there should be a decent number of them out there still. Our most recent tire special order was for the 47 SC for the B-25 main gear.

[Robbie Stuart]

How big a problem is that getting to be with these older FLYING warbirds? It really is a big safety issue as well as a cost issue. If getting "new" tires are being put off until they really need to be replaced, that is a problem! Small batch production "boutique" tires is an expensive thing as the market is so small. I read that our local Starfighters demo team is babying their supply of tires because of cost and short supply.

I wouldn't start jumping to conclusions. There's a dozen reasons tires blow out besides from being worn. Could have run over some FOD, or had a brake problem, sliced off a valve stem... I doubt very much that the airplane was flying around on bagged-out tires. The Stearman Restorers Association was recently able to get someone to make new production 10.00 SC tailwheel tires after the old molds were accidentally scrapped some years ago. They're Chinese, but a little work removes the obvious evidence.

The story I've been told (from a warbird pilot who was there) was that one of the propellers went into a "runaway" situation. The pilot wisely chose to abort the takeoff. In the ensuing attempt to stop the Lightning on the remaining runway, he had get VERY aggressive with the brakes. This is what caused the tire to blow. The tires were reported to be nearly new at the time of the incident.

That be the situation, things could have been a lot worse real quick.
On a sidenote; the 1st or 2nd P-40 my dad flew had a runaway propeller right after takeoff. He nursed it around & got back down, said it was real exciting there for a little while.

Robbie

[Holedigger]

Oops! Jumped the gun...Great job of stopping then in any case, going airborne like that would have been beyond "Exciting"!!

[Lightjug]

I seem to recall in Glacier Girl's restoration updates that they experienced something similar in 'locating' tires.

Question, I've heard the term 'runaway propeller' before especially when talking about the P-38 and the dangers it involves but could someone explain to me what exactly happens?

[Holedigger]

Good text book description from here
http://www.auf.asn.au/groundschool/propeller.html



The runaway propeller

As a propeller system increases in complexity, then the possibilities for malfunction increase. A problem associated with constant-speed propellers is governor failure during flight which, in most installations, will cause the propeller blades to default to a fine pitch limit. This greatly reduces the load on the power plant, and the engine will immediately overspeed, particularly if in a shallow dive. Depending on the fine pitch limit setting, the rpm of an overspeeding engine — sometimes referred to as a 'runaway prop' — may quickly go way past red-line rpm and, unless immediate corrective action is taken, the engine is likely to self-destruct and/or the propeller blades break away from the hub due to the increased centrifugal force.

The corrective action is to immediately close the throttle and reduce to minimum flight speed by pulling the nose up. (But see 'Recovery from flight at excessive speed'.) Once everything is settled down, fly slowly, consistent with the fine pitch setting, to a suitable airfield using minimum throttle movements. (The constant-speed propeller fitted to a competition aerobatic aircraft usually defaults to a coarse pitch limit to prevent overspeeding, but an immediate landing is required.)

[retroaviation]

(The constant-speed propeller fitted to a competition aerobatic aircraft usually defaults to a coarse pitch limit to prevent overspeeding, but an immediate landing is required.)

I witnessed that very thing happen to the late Marta Meyer, in her Giles G-300, while practicing for the U.S. National Aerobatic Competition, back in 1999 or 2000. While on the downline after a hammerhead turn, the engine went "warp nine" and she leveled out and made a landing. The digital tach only went to 3499 rpm, but had reached it's limit. There's no telling just how many rpm she went. Anyway, while removing the prop (which had to be replaced), I noticed all of the safety wire holding the retaining nuts was broken and every single nut was loose, due to the "stretching" of the bolts as the prop tried to "fly away" from the crankshaft.

I've also heard a few runaway props at Reno. A couple of Mustangs and a Lancair Legacy that was incredibly loud! All very scary stuff!

I'm glad the P-38 driver recognized it and was able to stop the airplane with no further damage.

Gary

[warbird1]

If that was indeed "Ruff Stuff", then our own WIXer, "gunnyperdue" is one of the pilots. I wonder if he was flying it when this happened? If he happens to be reading this, or anyone knows, some questions on the "runaway prop" scenario on the P-38:

1) Do the prop blades go to fine pitch on the P-38 in a "runaway prop" scenario?

2) Can you fully feather the prop blades on a P-38?

3) If you happen to get a "runaway prop" situation while airborne, what is the correction action? Can you use the bad engine, or do you shut it down?

If "gunnyperdue" is reading this, hopefully he can give his insight on what happened with some details.