What are the chances of a structural failure in a GA aircraft?

[Rally]

Just curious does anybody know what the chances of a structural failure (unprovoked) in a GA aircraft are? I am talking no aerobatics, storms, etc.

 

[CX880]

2% maybe

 

[Rally]

Every hour? Every 1000 hours? 2% what lol?

 

[stall022]

http://www.ntsb.gov/ntsb/

search "structural failures"

40 "structural failures" since 2000

 

[BoilerUP]

If the airframe is properly maintained and not operated in an abusive manner (ie "unprovoked")?

Slim to none.

 

[spudskier]

^^^ As stated above... also what are the chances this is posted in the wrong forum? Try looking for a better web site all together... there must be a mechanic's forum, a specific aircraft type forum (I'm sure you have one in mind) there are always bonanza owner web sites, etc...

 

[Amish RakeFight]

Keep in mind that one can adhere to limits and fly within the envelope and still experience a structural failure. This can stem from a prior flight (or repeatedly) where the plane was indeed 'overloaded' structurally without incident, leading to subsequent failure during normal operations.

Good maintenance and a thorough preflight are paramount to safety.

 

[rickair7777]

Keep in mind that one can adhere to limits and fly within the envelope and still experience a structural failure. This can stem from a prior flight (or repeatedly) where the plane was indeed 'overloaded' structurally without incident, leading to subsequent failure during normal operations.

Good maintenance and a thorough preflight are paramount to safety.

If an airplane suffered previous structural abuse which would be enough to cause a catastrophic failure during subsequent normal flight, odds are really good that such damage would be detectable during a thorough preflight.

Long-term salt-air exposure could cause damage to the underlying structure which might not be visible on a preflight. But if you operate in such an environment, hopefully your annuals will pay special attention to corrosion....it doesn't happen overnight, takes years.

But even with prior damage, I think the vast majority of failures also have some aggravating factor...serious turbulence, aggressive maneuvering, aerobatics.

 

[Flyer1015]

The Zodiac aircraft is a perfect example. A kit aircraft, built perfectly by the manual, and yet, there have been many fatal accidents with an inflight breakup. The aircraft wing flutters, and undampened, leads to vibrations that fail the wing inflight. This is an engineering flaw of the airplane, and a recommendation has been put out to ground these until the problem is fixed.

 

[DX Jake]

I guess it just depends, is it coke or hash? How many bundles?

 

[rickair7777]

The Zodiac aircraft is a perfect example. A kit aircraft, built perfectly by the manual, and yet, there have been many fatal accidents with an inflight breakup. The aircraft wing flutters, and undampened, leads to vibrations that fail the wing inflight. This is an engineering flaw of the airplane, and a recommendation has been put out to ground these until the problem is fixed.

I was assuming that the design was good...undamped resonance can destroy anything from airplanes to rockets to bridges and buildings.

 

[avbug]

Structural failure is a broad term.

I've seen spars crack, but I've seen the step snap off behind a wing, too. Both are structural failures...to which one do you refer?

I have no idea what the "chance" is that it will happen, but rest assured that it does, and will happen. Perhaps to you, perhaps not, but it does happen.

Numerous airplanes require airworthiness directives to replace or inspect spar caps. Few of them have been exposed to undue stress. I've seen cracks occur on a number of aircraft which weren't exposed to aerobatics or severe turbulence, but which cracked none the less.

Some years ago I maintained a fleet of 200 series Cesssnas. I found the vertical stabilizer attach brackets and points cracked, on every single airplane. The failed parts were aluminum, and after investigating the issue, the parts were re-fabricated in steel...which is how you'll find nearly all of them today. The cause of the cracking? Most likely pilots performing slips. Same thing they'd always been taught was safe...and is a lot harder on a structure than most realize. Never the less, a simple, standard general aviation technique.

Cracks and failues can result from overtightening a fitting (airplanes have lost wings that way), undertightening a fitting, using the wrong size bolt (saw a landing gear fail that way), from vibration, corrosion, metallurgical imperfections, and a host of other reasons. Two airplanes I used to fly both lost wings in flight, killing all on board. A large transport I used to fly experienced cracking throughout many of it's primary structural members. Two other light airplanes I flew had cracked spars, discovered by inspection...one completely cracked through in three places.

I couldn't tell you about the "chance," but that mechanical things will break, and parts fail; this isn't news.

 

[imacdog]

The Zodiac aircraft is a perfect example. A kit aircraft, built perfectly by the manual, and yet, there have been many fatal accidents with an inflight breakup. The aircraft wing flutters, and undampened, leads to vibrations that fail the wing inflight. This is an engineering flaw of the airplane, and a recommendation has been put out to ground these until the problem is fixed.

I thought a number of those failures had to do with the aileron cables not being rigged to the right tension? Still, it is not good to have the results that this plane has had.