Originally Posted by
Bell_ringer
The first two have nothing to do with inflight breakup.
The first is a prelim report with no conclusion and indicates loss of control with an unknown cause.
The second was poor maintenance resulting in loss of control on landing.
Struggling to find the relevance.
Stopped reading after that..
I was responding to gulliBell's assertion:
Originally Posted by
gulliBell
I'm not sure how many Bell helicopters breakup in flight with an experienced pilot/instructor at the controls. Probably zero would be my guess. The same can't be said for Robinson helicopters.
He guessed zero. I gave 13 examples just going back to 1994... some of these are clearly maintenance, some of them are design problems with the Bell product, and some of them (the smallest number) are probably due to the way the pilot was flying the machine.
The first one indicates what looks like a tail boom chop including strikes from both the main and tail rotor, and which is consistent with the witness' reports of a spinning nose low approach to the ground. Not sure if you disagree with the fact that the tailboom got chopped, or maybe you don't consider that an "inflight breakup". We can ignore that one if you want.
The third one says:
They subsequently reported seeing components separate from the helicopter before it descended and impacted the ground. The helicopter came to rest in a corn field approximately 1.2 miles from the departure point. A postaccident examination of the helicopter revealed that an 8-foot section of one of the main rotor blades separated in-flight rendering the helicopter uncontrollable.
which is certainly an in-flight breakup.
The next one, the Bell 222 actually mentions in-flight breakup:
The helicopter was on a postmaintenance flight when it experienced an in-flight breakup about 8 minutes after departure
and although it happened on a post-maintenance flight, if you read the report it was not a result of maintenance, but of a pin that was subject to hydrogen embrittlement.
The one after that I think I pasted an incorrect link, but the the 214 accident after that says
There was no evidence of abnormal engine operation at the time of the accident or a failure of the tail rotor system or a major airframe structural component before the in-flight breakup.
They have a theory about why it happened but the root reason couldn't be determined due to the post crash fire.
The one after THAT, the 222 quote:
The helicopter experienced an in-flight break-up when it was traveling at about 130 knots at 960 feet above the ground.
due to a fatigued pin quote:
A factor was the manufacturer's dissemination of the pin which did not meet dimensional standards.
i.e. Bell screwed up.
The one after that, the 212:
They then observed the main rotor blades contact the tail area, and the aft tail boom and tail rotor separate. Shortly after this, the main rotor separated and the helicopter descended and crashed to the ground.
i.e. an in flight breakup.
Another 212:
The main rotor mast displayed evidence of a mast bumping event, with indentations corresponding to the blade stops.
and the probable cause:
the in-flight separation of the main rotor mast while in cruise flight following a mast bumping event. The reason for the mast bumping event was not determined.
The 407 after that seems to be a tail boom chop by the tail rotor... whether it "broke up" is conjecture since no-one was around to see it, but all but 3 feet of the tailboom was separated from the fuselage - I'd call that in flight breakup.
The 206L1 after that was a boom separation due to fatigue cracks in the attachment structure.
The next, a UH-1B the probable cause finding:
A fatigue fracture in the main rotor mast, which resulted in an in flight separation of the main rotor from the helicopter.
The 206B after that was
THE AIRCRAFT HAD EXPERIENCED AN INFLIGHT SEPARATION OF THE VERTICAL FIN AND SUBSEQUENT MAST BUMPING
due to corrosion.
The last one, a 212
THE INFLIGHT SEPARATION OF THE MAIN ROTOR SYSTEM AS RESULTS OF THE
MAIN ROTOR STATIC STOP CONTACTING THE MAST FOR UNDETERMINED REASONS.
The relevance is that gulliBell postulated that zero Bells had broken up in flight with an experienced pilot at the controls, and I gave some examples of cases where that was wrong. I like Bells, I feel safe flying the B206B3 and B206L3, and given the chance to fly a 407, 222, 214, 212, or UH-1B I would, but to say that Robinson has all the in-flight breakups and other manufacturers do not is demonstrably not correct. I also am not trying to pick a fight with anyone... I'm just responding to a fairly extreme position with some data that says all manufacturers have issues with their designs...