Wessex Accident - Blades ??

[Pac Rotors]

According to the national newspaper this morning the CAA are looking at the possibility that the blades on the Wessex that crashed here in New Zealand recently might have been unairworthy as they put it.

More on this when it comes to hand.

[jr206]

I had the chance to see the Wessex in Motueka a few months ago.
The blades "looked" really dodgy.
They had some sort of rubber boot on the leading edge and it looked very buggered.
Not sure if this means anything... as I dont know much about the helicopter

[Pac Rotors]

Lot of rumours going around about the aircraft and owner but not sure if there is anything to substantiate it so it is only speculation at this stage. Still it didnt help the poor bastard that got killed. Makes you wonder just what the heck they are paying those idiots in Lower Hutt for.

[Hydraulic Palm Tree]

The Wessex has a Nitrogen charged main spar in the blades. This is checked by operating a blade integrity monitor (BIM) at the root.

Just for info

[Larry]

HeavyLift Inc. lost a CH-54A Skycrane(N64KL)
in 1998 with the loss of the entire crew
because of a lack of attention to a BIM indicator showing a possible leak.
Heres a link to the accident report. Its a lesson for all to learn from. :mad:

http://www.ntsb.gov/NTSB/brief2.asp?ev_id=20001211X10621&ntsbno=LAX98FA236&akey=1

I took photos of N64KL a few months before the tragic accident.At the time it was working a US Forest Service fire in San Bernardino Calif.using a 2000gallon Bambi Bucket.

http://www.helispot.com/photos/01742.jpg




[This message has been edited by Larry (edited 20 February 2001).]

[mrfish]

Pac Rotors:

What type of Wessex are they operating. Assume Wessex5??

[Lu Zuckerman]

To: Larry

Disasters can stem from the smallest screw up or the smallest omissions in a procedure. Many years ago a US Marine flight crew was in process of folding the blades on a HRS that had just landed. When they turned the left blade over it broke off at the root. The failure was traced to a woman working in the blade shop at Sikorsky. She was using an Xacto knife to remove excess bonding material that had oozed out from under the retention strap on the blade and in the process cut into the Anodized coating on the spar setting up a stress riser. This improper operation caused the scrapping of several hundred blades including one on a HO4 S that I was crewing on.

In another case Los Angeles airways lost two S 61s both for the same reason. The cause of both crashes was the failure of a spindle resulting in the in-flight loss of a main rotor blade. The cause of this failure was traced to Sikorsky performing an inadequate overhaul on the spindles of both rotorheads.

If in fact the CH 54 blade failed due to a crack propagation from the drilled hole, then the fault and blame lies with the individual that performed the illegal operation and the firm that he worked for inadequate quality control. If the loss of internal spar pressure can be traced to leakage from the crack that propagated from the drilled hole it would require a second failure for the leak to manifest itself. That second failure would be the cracking or degradation of the bonding material that held the pocket onto the spar. The only option open to the CH 54 maintenance crew was to remove the blade and scrap it as they would never be able to detect the crack without using some trace element in the Nitrogen and using electronic sniffers to detect the location of the leak. In place of that, they could have scrapped the blade. Because the accident occurred when the helicopter was returning to base it is not known if they would have performed the sniffer test or, scrapped the blade.

Speaking of drilling holes in the spar, the US Navy was guilty of just that. The Navy overhaul base in San Diego was attaching the pockets to the spars on HSS-1 main rotor blades using PK metal screws. All effected blades were scrapped.



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The Cat