UH-1H Main Rotor Flapping

[instructor-pilot]

I had an accident where main rotor blade hit the tail boom just behind tail boom attachment points.during the investigation it was found that the main rotor blade hit the tail boom but because the tail boom is not severed (completely broken) and they believe that blade would hit the tail boom much more backward somewhere close to the ailrone so it had to happen during rolling of the helicopter.how could i proof that it had happened in the air.just before that i think that must rocked forward.collective up was applied to hard and cyclic was moved abruptly back.

[hueyracer]

Was that the same accident, or did you manage to get into another one?

[Ascend Charlie]

Get a model of the aircraft, or any helicopter.
Bend the blade down and see where it hits the tail boom. A light touch would be the tip of the blade touching the boom back behind the elevator.
A more solid hit, cutting the driveshaft, will be further forward.

To hit the tail boom near the attachment points, the whole blade must chop through the boom. Unless of course, your blade has a weird downwards v-shaped bend in it, which just allows the v to touch the cone but the rest of the blade misses the boom.

I spek from experience, I chopped off a boom, right where the sign says "Danger."

[technoprat]

Do you have a photo of the damage to the boom.
A picture speaks a thousand words.

[SASless]

To cut the boom close to the attach points would require some very interesting forces....and the sheer length of the blade would make one suspect it would have had to hit the ground along with the tail boom.....if the aircraft was in contact with the ground with the skids.

Also...it would seem there would have to be indications of the rotor head hitting the mast as well along with other damage.

[Senior Pilot]

SASless,

I suspect it may be in reference to Bosnian UH-1H crash (http://www.pprune.org/rotorheads/489143-bosnian-uh-1h-crash.html) and this tailboom damage: but instructor-pilot may want to confirm my suspicion?

http://nationalpostnews.files.wordpress.com/2012/06/bosnia-helicopter-crash.jpg

[SASless]

If I read the accident description correctly in the other thread....my for what it is worth guess is the tail boom got hit by a fractured blade following the blades hitting ground and coming apart.

I have to admit that is about the most unusual parking position I have seen a Huey in....and should get some Attaboy's for difficulty and execution!

Huey Main Rotor blades are pretty stout and to see them peeled back like that is interesting to say the least.

Flying with student at qualification trg
Task - simulated engine failure at altitude
After initial, not ideal-student overrides me, I stopped that, nose turns right 20-30 deg then abnormaly continues turn
Hanged with left skid lower
At 110 deg i put collective down thought tail rotor had failed
Contacted ground with left skid inertially moving backward
Rolled on the left side
Blade hit the ground and broke

[B Sousa]

Inverted Backcourse ILS to a full stop. I have heard about that approach, but never seen it.

[hillberg]

If that's the question of the tail boom strike, No the roll over displaced the main gear box-all bets are off, now scrach its belly and take it for a walk.:rolleyes:

[tottigol]

SAS, it seems that in this case the skids are NOT in contact with the ground.:}

Rule #1: keep the dirty side down, was not respected in this instance.

Glad everyone walked out of it.:D

[Takan Inchovit]

A mast bump ripping out the whole transmission in the air?

[SASless]

Bert Baby.....I did come to a stop and back back up the ILS in a Chinook at Milan/Malpensa International one night! We were doing GCA's with the Controller at the time and the GCA and ILS were set to the same parameters so it was easy to stay on course and glide slope while backing up at a fair old clip.

Luigi went from English to Italian and rather confused in his chit chat to us about our progress "down" the approach! Youthful exuberance was so much fun in those days!

I have flown an ILS inverted in a Sim before....but an inverted Back Course approach.....now that woud be interesting!

[[email protected]]

SaS, we used to do this to wind up the air traffickers at RAF Shawbury (where both helo pilots and ATC are trained) on the PAR - always a laugh to hear their commentary falter and then dry up completely:)

[Arm out the window]

"You are dangerously below glide path, I cannot control you further ... look ahead and crash visually."