Good pics of the crack included in the report referenced above.
Damb lucky the blades didn't fly off - that crack is amazing!

R22 main rotor blades
 

Im interested in how different pilots manage to inspect the main blade roots top and bottom. I would agree that inspecting the underside is not difficult but the top may be, especially for the shorter person.

Bouncing a Robinson
 

Given that the placard on the end of the blades says never pull down, does one assume that because to main head bolt is torqued up so as to require 10ft/lb force to rock the head that pulling the blades down places an unacceptable load at their root. If this is the case. what risk is there in pushing a machine over bumpy ground causing the blades to deflect their weight (about 30lb). Or am I making a fuss about nothing.

Yes.
None.
Yes.
:)

!!!!e - looking at cracks like that makes me even more determined not to get back into a Robbie.

:E

Another reason for thorough preflight...
 

Correct me if I'm wrong, but during R44 pre-flight - you don't even climb on top to check the pitch change links or anything else on the head. I believe it is just a visual inspection from the ground? I don't fly the R44, so my memory from RHC course might be off on that ship. Anyway, people complain because I take almost a half an hour to preflight an R22. They can get bent (my a$$ = my rules)!

Force increases friction.
 

To: bugdevheli

The design of the Robinson head is such that with the blades in the static position the spindle tusks are hard against the droop stop through bolt. Considering the lever arm of the blade which has its fulcrum at the cone hinge the force on the contact point of the spindle tusk and the droop stop through bolt is quite high. Trying to pull the blade down by the tip amplifies the contact pressure and could cause damage to the blade due to bending or possibly damage the spindle tusk due to abrasion.


:E

Little cracks grow to be big cracks.
 

Back in the early 1950s two Marines were folding the blades on a HRS (S-55) and when they turned the left blade over it fractured at the intersection of the spar and the first pocket. This helicopter had just completed a flight. The crack had propagated from a very shallow cut into the anodized coating on the spar and had resulted from an employee removing excess bonding agent using an Exacto knife. The helicopter I was crewing was aboard ship and we were to fly back to our base, which was about ten miles away. Our flight was cancelled until a Sikorsky rep could come out to inspect our blades. He found the mark of the Exacto knife on one of our blades. After he had ground the cut out we flew back to the base and we scrapped the blade.

But then again it also happens to aircraft. This was filmed on TV. A B-52 had just returned to base after a lengthy flight and the crew was walking away from the plane when the left wing broke away from the wing box.

:E

I cannot believe ANYONE would not check the rotor head CLOSE UP during a check A, nor the top of the blades of any helicopter.

Are you lot stupid or what???????????????

Don't tell me...you weren't shown it during your conversion, so it's not necessary :eek: :*

Whooaaa... easy there, Trigger! My point was that when I preflight the R22, I take extra time and definately include the top, rotor head, nook, cranny, and small areas barely big enough for a ferrit. However, on the R44 - I don't believe it is part of the normal preflight procedure to inspect the top. Since I don't fly the R44, I could be wrong. However, when I went to the RHC Safety Course (last year), we asked about how to inspect the top of the R44. The response was that it wasn't required, and that a visual inspection would do (but you could get a step ladder and look if you wanted to).

My point is... better safe than sorry - and as PIC, you should take as long as you want for preflight. Some folks fault me for taking up to 30 minutes to preflight an R22, but that is their problem - not mine. (My a$$ = my rules).

Whats wrong with a ladder?:sad:
or is everyone just to lazy to bother?

Looking at that crack, that particular R22 was possibly only seconds aways from a total separation, and it makes you shudder to think that some ham fisted techie with a craft knife can bring about some serious failure such as that.

Is it possible for any actual blade failures to be checked back to see if this sort of damage was evident, at or around the separation point? or am I expecting too much!:ooh:

Vfrpilotpb: The blades of all helicopters are highly stressed, particularly the inboard half, the damage tolerance is far less in that area, as opposed to the area closer to the tip.

One of my first experiences with an R22, was to find a crack on the underside of a blade. It was started by a fairly small dent from an ejected rifle bullet casing some nine months earlier.

Dent to massive crack in about 30 minutes.
 

A Coast guard HO3S-1G was dispatched from Grand Isle, Louisiana to remove several crewmembers from a sinking shrimp boat. On the first flight out one of the blades severed a mast guy wire on the boat. Upon return to base the blade was inspected and found to have a small dent on the leading edge of the blade. The damage was removed per the maintenance manual and the second flight was made to remove the remaining crewmen.

Upon return to base the blade was found to have a crack that had propagated from the leading edge of the spar to almost the rear edge of the spar. The blade was removed at the same time that the pilot changed his underwear. The damaged section was cut out and sent back to Sikorsky with the thanks from the flight crew for building such damage tolerant blades.

:E

Bouncing a Robinson
 

Thomas coupling:D , shame on you, " yes," " none," "yes." good heavens man, a question like that requires an in depth answer, calculations, examples, quotes from fellow pilots. How are Newpruners going to be educated if we are not privvy to your wonderfull verse

It is my semi-learned opinion that if the blade flexes down a given distance, either by a meaty hand pulling, or by an inertial force during a tow across a rough field, the stress on the mechanism is the same.

Of course, the limitation on routine pulling of blades, once per pre-flight inspection could be based on the many repeated cycles of damage the blade mechanism would accrue. OTOH, I have heard of some homebuilts where the blades must be supported in a crutch for tow operations due to these stresses.

I forgot to add this to my post above.
 

In addition to the increased load generated between the spindle tusk and the droop stop through bolt the forces exerted on the through bolt when the blade is pulled down are transferred to the teeter bolt increasing the friction load. This further exacerbates the problem. If you want to lower one blade you must raise the opposite blade.

It is the combined friction of the spindle tusk on the through bolt and the friction applied to the teeter bolt that maintains the blades in the static condition.

:E

About fifeteen years ago, the Trump organisation lost an A109 and all onboard when a blade gave up. Allegedly investigation found that during manufacturer an over zealous operative induced a hairline fracture in the blade spar by removing bonding agent with a knife.

Absolutely frightening that we as an industry continue to make the same mistakes!

Maybe bonding agent needs to be sanded off. can the manufacturer be sued for these problems?
it sounds like a manufacturer liability and quality control problem.

Bond, James Bond.
 

The removal of excess bonding material is purely cosmetic. The bonding agent that oozes out from faying parts will not hurt anything. That is if it is at the root end of the blade. If it is at the tip then QC should catch it and a suitable means of removing the excess must be established by engineering.


:E