And then, the rotor broke off

[Lu Zuckerman]

To: Where are you now?

In 1976 or there abouts you were an American pilot working for Bristow Helicopters on assignment to The Imperial Iranian Air Force teaching students to fly helicopters. On one training assignment you wanted to demonstrate autorotation. The student was slow to respond and you lost rotor speed. You dove the helicopter to build up rotor speed and at the same time you tried to engage the engine but it wouldn’t connect as the freewheeling unit had been damaged during two compressor stalls that had gone unreported. You made a successful run-on landing and while the rotor was spooling down you filled out some paper work. It was at that time the mast fractured and the rotor came off hitting the pylon and then the stabilizer bar came crashing through the right side of the fuselage. You and you student were the first flight crew to survive a mast separation on a Bell helicopter or, for that matter any helicopter

Please note, if the stabilizer bar penetrated several inches further forward you would not be able to respond to this post.


------------------
The Cat

[UNCTUOUS]

I remember just before my UH-1B Squadron had a series of inflight rotor separations, that the Engineering Officer came into the crewroom and had us look down inside a supposedly serviceable mast that had been just removed from a machine I'd flown the day before. It appeared alarmingly ovulated via that internalised view (holding it up to the light) but you just couldn't tell it by feel or appearance on the external viewing. Within days we'd lost the first crew and there were to be two more before we stopped flying and waited on Ma Bell's boys to find the fix. Supposedly this was "no more touch-down auto's (with floored collective and mast-bumping on rollout)"
The hierarchy wouldn't go along with that but luckily we got some D models to play with. We were very ignorant. No one told me that if I used a downwind hover reference that the hot air pooling around the T/R drive-shaft hangar-bearing beneath the jet efflux would cause a lubrication breakdown and a tail-rotor drive-shaft failure in a 120 ft hover. But it was always easier to learn that way, because you never forgot.

[Ancient Pelican]

A classmate of mine rewrote the emergency procedure for low transmission oil pressure in the Huey, of course him and his crew and seven other souls weren't around to read the change when it was finally published.

Is this where the phrase "hard won knowledge" came from?

Oh, how much do we owe those who have gone before?

There but for the grace of God go I.

Yeah, but I still love these things!!!

[Ancient Pelican]

Lu, the Cat,
Would you be interested in reading "Sikorsky Helicopter Flight Theory For Pilots and Mechanics" by John Montgomery, dated 1964.
As an observer of the industry I thought you might be interested.

[Lu Zuckerman]

To: Ancient Pelican

I have a copy of the blue book sitting in front of me right now. I have been quoting from it for several days now and many of the participants on another thread state that it is wrong. I told them that if I were proved wrong in quoting from the blue book I would crash and burn and Sikorsky would accompany me on the ride down.

When I first worked at Sikorsky the blue book had about 20 pages and Ralph Lightfoot wrote it. Now the latest version that I have has 100 pages and is written by John Montgomery and is dated 1964. That shows you how much their understanding of helicopter flight theory has expanded.

Thanks for the offer.


------------------
The Cat

[This message has been edited by Lu Zuckerman (edited 26 January 2001).]

[This message has been edited by Lu Zuckerman (edited 26 January 2001).]

[Lu Zuckerman]

To: Unctuous

At the time of the incident I posted above Bell Helicopters (206s and 205s) had experienced 53 mast separations. To date Robinson helicopters have experienced 35 and the last four were in the year 2000.

------------------
The Cat

[Ancient Pelican]

We have the same book, there can't be that many copies of it, are there?

[Lu Zuckerman]

To: Ancient Pelican

They give a copy to everyone that goes through the service or flight schools. Most likely the tech reps pass them out as well. You can even get a copy by calling the service department. That's how I got mine.

------------------
The Cat

[helimutt]

Mast separations? in a Robinson? Surely you must be mistaken? Either that or I must be mad for flying them!


[This message has been edited by helimutt (edited 26 January 2001).]

[The Nr Fairy]

Helimutt :

Don't start a wind-up, we'll never see the end of the thread :)

[Lu Zuckerman]

To: Helimutt

That’s right, mast separations and / or rotor incursions. There have been 35 to date.

If you check the last page of your POH you will see restrictions dealing with sideslipping and flying out of trim. Elsewhere you will see cautions against zero G and cautions against moving the cyclic aft in countering zero G. All of this stems from a report prepared by the Georgia Tech Aero Department for the FAA. As a result the NTSB wrote a report; SPECIAL INVESTIGATION REPORT. ROBINSON HELICOPTER COMPANY R22 LOSS OF MAIN ROTOR CONTROL ACCIDENTS. The report number is PB96-917003/NTSB/SIR-96/03.

The report outlines in detail what happened to the first 31 helicopters covered in the report. The last 4 rotor loss / rotor incursions happened last year. One in California, one in the UK, one in Scandinavia and one in Ireland. I wrote a report and submitted it to the NTSB outlining my thoughts on what I thought was the cause of these accidents. I offered the report to members of this forum and the S**t hit the fan. Most of the S**t was thrown by Robbie lovers and some from others that just like to throw S**t.

If you want, contact the NTSB and they will provide the following; the report but it might cost you and a printout of all of the Robinson accidents involving rotor loss or rotor incursion.

This information is dated and the name may have changed but the rest is OK.

Latricia Carter RE-50
NTSB
490 L’Enfant Plaza S.W.
Washington, DC
20594-2000

Telephone number 202 314-6000
Ask for her by name or by department number.

The official name of the department is Aviation Accident Data Specialist Analysis and Data Division.


------------------
The Cat

[Lu Zuckerman]

There were several other bizarre incidents involving rotor blades. In the early 50s a marine HRS (S 55) landed and per base orders the mechanics had to fold the blades. The blade on the left side had to be flipped upside down in order to fit the blade into the saddle on the side of the tail cone. When they flipped it over, it broke off. The fault was traced back to a woman working in the blade shop who was removing excess bonding material using a Xacto knife. In the process of removing the material she cut into the anodized film on the spar and it set up a stress riser. At the time of the incident I was crewing an HO4 S (S 55) on an Icebreaker in Lake Michigan. We were ordered to not fly until a Sikorsky rep and an engineer could inspect our blades. When they performed the inspection they found that one of our blades was effected with the scribe mark. They ground it out and we were authorized to fly back to our base. When we got there we scrapped the blade.

On another occasion several years later a Coast Guard HO3 S (S 51) was dispatched to a rescue mission off of Grand Isle, Louisiana. On the first pass to hoist two fishermen they hit a guy wire that supported the mast. When they landed, they inspected the blade and discovered a knick in the leading edge of the spar. They burnished it out in accordance with the MM and made two more recoveries. When they got back to base, they found that the knick had developed into a crack that almost radiated to the rear of the spar. They cut that section of the blade off and sent it to Sikorsky with a thank you note from the crew.

A TV crew that was on an American SAC base recorded the most bizarre incident of all. A crew was walking away from a B 52 that had just landed and the camera caught them as they left the aircraft. They didn’t see it but the camera did. The left wing broke off at the root and dropped to the ground. The crew turned around and was horrified. I would imagine at least one of them had to change his underwear when he got back to his quarters.


------------------
The Cat