Why did the wings on this Cessna 150 separate from the aircraft in flight?

Question

A while back I asked if the wings ever fall off Cessna 150s and I got some joking replies. I expected that.

However, I did find a few instances where the wings did fall off of a 150 in flight. (Nearly always in a uncontrolled flight.)

This is the latest:

I am not for sure, but from what can I ascertain is that the pilot lost control of the aircraft in a fog and in the ensuing dive the stresses exceeded airframe parameters and the wings tore off. I guess it does happen!

Am I reading the report right?

http://www.ntsb.gov/ntsb/brief2.asp?ev_id=20060917X01355&ntsbno=NYC06FA215&akey=1

Answer 1

There are three ways to do that; overspeed the airframe, load to many G's or fail to have thorough annual inspections done. Since both wings appear to have failed, my guess would have to be with one of the first two.

Some models of the 150 are not approved for spins, the M model that a buddy of mine owned comes to mind, and some weren't approved for spins with full fuel, max gross weight or CG within the envelope but too far forward or aft.

Private pilot training typically tries to teach enough to fledgling, VFR pilots if they inadvertantly find themselves in IFR conditions. It doesn't teach much more than that.

Reading the report, which states that the wings were sheared away in an upward direction, and showed signs of being over stressed. The Pilot's report to ATC of suspecting he was inverted leads the reader to believe that he wasn't paying sufficient attention to the pumpkin, his turn coordinator or whiskey compass.

The low time, VFR pilot appears to have flown boldly into clouds despite not being certified to, experienced vertigo and rolled the airplane onto its back resulting in an inadvertant dive.

The dive lead to airframe stressing speeds, and as the aircraft departed the cloud layer and the pilot was able to visually detect ground, he applied sufficient force to the control yoke to cause sufficient G's to cause the wings, and upper fuselage, to seperate from the rest of the airplane

From that point on the remaining fuselage, engine, prop and empenage were ballistic, and the wings as stated in the synopsis, would "twirl" in the air as they alternately stalled and made lift in their descent, free of the aircraft.

The reports of the airplane being fueled with Mogas are irrelevant. Mogas being detected in the wing tanks is irrelevant.

The pilot pulled a "Kennedy", flying into IFR conditions without IFR training, suffered spatial disorientation, and by indicating that he thought he might be inverted, obviously disobeyed one of the first things taught in ground school; trust your instruments, not your *ss.

There being no further detectable mechanical discrepancies with the recoverable portion of the aircraft or instrumentation suggests that this pilot wasn't merely exceeding his endorsements, he was ignoring his instruments. All of which are cardinal no-no's.

Deliberate flight into IFR conditions without training, experience or instrumentation for IFR conditions, failure to properly understand and trust the instruments despite ground schooling and testing as well as a check ride, all suggest that this pilot killed himself, a passenger, and ruined a perfectly good airplane through his disregard for safety.

The wings will break of anything from a Stearman to an A380 if you manage to do something stupid enough. A Stearman's a little more difficult, (they were only tested to 12G's because there wasn't equipment sophisticated enough to stress them beyond that,) but it can be done.

My personal favorite is this one;
http://www.ntsb.gov/ntsb/brief.asp?ev_id=20001212X18632&key=1

Answer 2

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Aircraft are built differently than other machines. The wings of an aircraft are built much like the axles of a vehicle -- strong and sturdy, with room for tolerance in the event of an emergency. Much like a vehicle, tolerances can be pushed and parts can fail, though in an aircraft those tolerances often require pushing the aircraft or crew past the envelope of personal tolerance. In a nutshell, yes, you can "break" the wings off of an aircraft. However, the Cessna 150 has a very low weight to lift ratio, meaning that the actuall stress on the wing per square inch is very low and highly over-engineered. In fact, the Cessna company chose the 150 as the preferred model for the "Cessna 150 Aerobat," an aircraft designed for simple aerobatic flying. If A.D.'s (aka Airworthiness Directives) are maintained by the owners or operators of the aircraft and proper mandated maintenance is performed, it's fairly safe to say that your 150 is safe. Remember, hours in the air doesn't neccesarily mean wear. The low weight to lift ratio = low metal fatigue, and aircraft don't wear like vehicles do as the medium for flight is simply air.

Answer 3

The NTSB report gives some clues: "The pilot held a private pilot certificate with a rating for airplane single engine land, which was issued on June 17, 2006. His most recent FAA third class medical certificate was issued on February 16, 2006. He did not hold an instrument rating."

He was a new pilot, not instrument-rated, and he apparently got into cloud and lost control of the airplane. Once you've done that, you can break nearly anything. It's not often the airplane's fault, either. In cloud, you have no idea if you're in a turn or not, unless you pay attention to the instruments. He probably didn't know what he was looking at or he was so disoriented that he couldn't remember his minimal training. Also, most C-150s don't carry much instrumentation. The NTSB report doesn't mention instrumentation, so it's impossible to see if this was a contributing factor.

At any rate, once you're in a cloud, you can't fly. (Don't believe me? Ride your bicycle with your eyes closed!) If you over-stress the airplane, it WILL break. It's impossible to say exactly what happened in this case, but I know which way I'd bet.

Answer 4

Cessna 150 Wingspan

Answer 5

You read it right. 9 out 0f 10 times, the pilot has continued flight in instrument conditions, in which he is not qualified to fly in, gets spatial disorientation and crashes the plane. If the pilot finally looks at the instruments and determines the airplane is in a dive, he will instinctively pull up and break the airplane.

Answer 6

Sounds like he lost his ground reference, panicked and over-controlled the bird. Full up elevator above maneuvering speed can result in such a situation, especially a 150 with 2 passengers, and (presumably) full tanks. It totally sucks, but pilot error is a killer, have to keep your brain switched on.

Answer 7

Definitly. If you fly in a V Tail Bonanza and get into to too steep of a dive and pull up to quickly youll rip off the the V instantly.

Answer 8

I would like to ask the same question as the user above.

Answer 9

I do believe jettech hit the nail on the head.