number of rotor blades

Dave Jackson wrote:
Sikorsky has a couple of patents for 'Rotor system having alternating length
rotor blades'. [U.S. patent #5,620,303]

This is not to suggest that the removal of a portion of the blade on the
ground is the same as the removal of a portion of the blade in the air.



I can garantee that any of these designs still keep the rotor system
balanced.

SORRY BOB! GUESS MY MEMORY IS FAILING. HOW COULD I FORGET THAT THE
AIRCRAFT THAT DONALD'S PEOPLE WERE USING THAT DAY BACK IN 1989 WAS LEASED
AND NOT OWNED BY TRUMP. I DIDN'T REALIZE THAT THE ACTUAL OWNERSHIP OF THE
AIRCRAFT WAS REALLY THAT CRITICAL TO THIS THREAD ON M/R BLADE FAILURES. ONE
WOULD THINK THAT YOU WOULD HAVE REMEMBERED THE CAUSE OF THE FAILURE AND NOT
HAVE THROWN OUT THAT "FORGING LAP" AS THE CAUSE. huh? JC

"Bob" wrote in message
...
IN CLARIFICATION TO THE ABOVE:

THAT WAS NOT "DONALD TRUMP'S AGUSTA THAT WAS LOST IN THE ACCIDENT UP IN
NEW
JERSEY. THAT AIRCRAFT WAS LEASED THAT DAY FROM PARAMOUNT AVIATION. TRUMP
HAD FIVE (5) OF HIS L A R G E HELICOPTERS SITTING IN THE HANGAR ON THE
DAY
THAT THE LEASED AIRCRAFT WAS LOST.

I WAS THE CHIEF INSPECTOR FOR TRUMPS HELICOPTER OPERATIONS AT THE TIME SO
YOU CAN TAKE THIS INFO TO THE BANK. HIS AGUSTA 109 WAS IN MAINTENANCE
THAT
DAY AND WAS UNAVAILABLE. THE BLADE THAT FAILED HAD A "FORGING LAP": LEFT
IN
THE M/R/B SPAR SINCE MANUFACTURE WHICH CREATED A "STRESS RAISER",
EVENTUALLY
A CRACK, AND THE REST IS HISTORY. For the rest of the commenters, now
with
many composite blades out there a better record can probably be expected
although no great inspection methods have yet been developed for
composites.
Metal blades departed aircraft many many times, hence Sikorsky's "BIM"
indicators on the blade roots. Hundreds of thousands od pounds of
centrifugal force and cracked blades will always present a problem, huh?

Hey JC er...excuse me HELIMECH

If you had followed the thread you would have seen that the EXACT CAUSE of
the MRB FAILURE WAS CLARIFIED BY ME, not that I would suspect that you might
have caught it seeing that you're still mentioning a "forging lap". The
executives lost in that flight, were known by me and it was QUITE ironic
that they lost their lives in a chartered aircraft. DESPITE YOUR OBJECTION
to my clarification as to the aircrft owner I'm SURE I presented more
factual information as to the cause of that Main Rotor Blade failure, and
others, than any other contributer to that particular subject. By the
way...refresh my memory as to the contextual wisdom of whatever you may have
CONTRIBUTED.

Bob

My objection was not your clarification to the owners it was the WAY IT WAS
TYPED. Must be a QA thing. JC

"Bob" wrote in message
.. .
Hey JC er...excuse me HELIMECH

If you had followed the thread you would have seen that the EXACT CAUSE of
the MRB FAILURE WAS CLARIFIED BY ME, not that I would suspect that you
might
have caught it seeing that you're still mentioning a "forging lap". The
executives lost in that flight, were known by me and it was QUITE ironic
that they lost their lives in a chartered aircraft. DESPITE YOUR OBJECTION
to my clarification as to the aircrft owner I'm SURE I presented more
factual information as to the cause of that Main Rotor Blade failure, and
others, than any other contributer to that particular subject. By the
way...refresh my memory as to the contextual wisdom of whatever you may
have
CONTRIBUTED.

Bob

JC...
Your point is humbly acknowledged. I really have to stop HOLLARING every
one of the buzillion times somebody says sommething like "hey remember when
TRUMP's Agusta crashed?" Considering that my name is plastered all over
that lAgusta's logbook, and as far as I know it's still tooling around
someplace, you might understand why it kinda ruffles my feathers.
Bob

Completely understand. If its any consolation I will now never forget that
it was indeed a leased aircraft. (course I'm getting old and the my memory
is not quite what it used to be but I'll try) Cheers, JC

"Bob" wrote in message
...
JC...
Your point is humbly acknowledged. I really have to stop HOLLARING every
one of the buzillion times somebody says sommething like "hey remember
when
TRUMP's Agusta crashed?" Considering that my name is plastered all over
that lAgusta's logbook, and as far as I know it's still tooling around
someplace, you might understand why it kinda ruffles my feathers.
Bob

"Helimech" wrote:

About 2 years ago Herman Hospital in Houston, TX lost a BK117 due to a M/R
blade loss. They were on approach, I seem to recall about 100 ft AGL, and
broke a TT strap (badly corroded). The M/R gearbox left the aircraft and all
3 souls were lost.

Ok another question. What is a TT strap?

Dennis.


Dennis Hawkins
n4mwd AT amsat DOT org (humans know what to do)

"A RECESSION is when you know somebody who is out of work.
A DEPRESSION is when YOU are out of work.
A RECOVERY is when all the H-1B's are out of work."

To find out what an H-1B is and how Congress is using
them to put Americans out of work, visit the following
web site and click on the "Exporting America" CNN news
video: http://zazona.com/ShameH1B/MediaClips.htm

The Tension-Torsion (TT) straps are basically 2 bushings a certain distance
apart connected together by thousands of turns (I've heard something like
12,000 turns) of stainless steel wire (around .020" dia.), sealed in a
plastic like covering. These straps (one for each blade) are what hold the
main rotor blades to the rotor hub. The straps have to handle the huge
centrifugal loads (tension) of the blade but still allow for pitch (torsion)
control inputs from the pilot. Here is a link to Lord Corporation and a
picture of some TT straps. Lord is the present manufacture of the straps
for the BK117 and BO105. The strap that failed in Houston was made by
Bendix. http://www.lordmpd.com/aerospace/rot...ion_straps.asp

Hope this helps, I'm sure someone could describe a TT strap better but this
is the best I can do this early in the morning. JC



wrote in message
...
"Helimech" wrote:

About 2 years ago Herman Hospital in Houston, TX lost a BK117 due to a
M/R
blade loss. They were on approach, I seem to recall about 100 ft AGL,
and
broke a TT strap (badly corroded). The M/R gearbox left the aircraft and
all
3 souls were lost.

Ok another question. What is a TT strap?

Dennis.


Dennis Hawkins
n4mwd AT amsat DOT org (humans know what to do)

"A RECESSION is when you know somebody who is out of work.
A DEPRESSION is when YOU are out of work.
A RECOVERY is when all the H-1B's are out of work."

To find out what an H-1B is and how Congress is using
them to put Americans out of work, visit the following
web site and click on the "Exporting America" CNN news
video: http://zazona.com/ShameH1B/MediaClips.htm

Having a picture certainly helps, but I'm still confused as to where
exactly that they go. First, are we talking about a semi-rigid or
fully articulated or other hub?

Essentially, it looks a lot like a box end wrench. However, in
function, it sounds a lot like an elastomeric bearing.

Do you know of any closeup photos with TT straps installed on the hub?

Dennis.


"Helimech" wrote:

The Tension-Torsion (TT) straps are basically 2 bushings a certain distance
apart connected together by thousands of turns (I've heard something like
12,000 turns) of stainless steel wire (around .020" dia.), sealed in a
plastic like covering. These straps (one for each blade) are what hold the
main rotor blades to the rotor hub. The straps have to handle the huge
centrifugal loads (tension) of the blade but still allow for pitch (torsion)
control inputs from the pilot. Here is a link to Lord Corporation and a
picture of some TT straps. Lord is the present manufacture of the straps
for the BK117 and BO105. The strap that failed in Houston was made by
Bendix. http://www.lordmpd.com/aerospace/rot...ion_straps.asp

Hope this helps, I'm sure someone could describe a TT strap better but this
is the best I can do this early in the morning. JC




Dennis Hawkins
n4mwd AT amsat DOT org (humans know what to do)

"A RECESSION is when you know somebody who is out of work.
A DEPRESSION is when YOU are out of work.
A RECOVERY is when all the H-1B's are out of work."

To find out what an H-1B is and how Congress is using
them to put Americans out of work, visit the following
web site and click on the "Exporting America" CNN news
video: http://zazona.com/ShameH1B/MediaClips.htm

look he
http://www.star-techno.com/clsc/206B%20hub.gif