350 Star Failure - Texas

[twinstar_ca]

We are changing our's as we speak...nice crack on one arm found during DI

 

i'm glad you found it pre-flight as opposed to posthumously.. sounds like this is area that gets not thought about often until something is found by somebody... if talking about blade tying makes one other person review their methodology, it's been a very successful thread...

[PerfectTrack]

What Blackmac said (bless his heart we all still love him)

 

However, I feel you're fishing Sharky. So I'm just going to point you in the direction of the approved manufacturers manuals... Hope you're all reading them.

[T tail]

I've always been told to always tie the Astars blades down as flapping damages the Star Flex?? I've seen 500 blades tied down so tight I was surprised they weren't rippling under the pressure, can't be good them ?????

 

cheers TT

[vintagemilano]

This is a limit in the Astar manuals about how much you can tighten down the tie downs. After that you are supposed to use poles at the blade tip to ground and anchour that.

[Blackmac]

Vintagemilano:

 

Without getting into a long discussion, common sense has to prevail and it doesn't take a rocket scientist to figure out where your stress points are, or would you prefer that the blades kept the helicopter from lifting of the ground in high winds. (better be good blades)

 

Happened quite often on the Labrador coast we would shut down at a radar site and have a sixty to seventy mile an hour wind pick-up. All six blades of the chopper would be tied to the Vertol H-21 and two 45 gal of fuel tied to the front oleo to keep the nose from coming of the ground.

 

It's not the first time a manufacturer has goofed.

 

You might ask them to elaborate.

 

Cheers, Don

[vintagemilano]

No worries, just that being heavy handed can cause problems and cost money too.

[T55]

I'll have to check the books, but I seem to recall that the A-star manuals call for the high wind tie down kit for winds in excess of 30 mph or thereabouts... This involves poles under the tip of each blade, then cinching the tie down. Prevents stress from too tight as well as immobilizes the blades from flapping. I've yet to see one of these kits in real life, though.

[PerfectTrack]

to save you guys from speculating for weeks on end, go see your engineer (ask him nicely) and refer to MET 10.00.00.301 and 302. If by chance you are the engineer and you're wondering yourself, the next time you're on a seismic job wacking it in the back seat of the crew truck, lay down the hustler, pull out the MET and familiarize yourself with it. If you don't want to do that, become a senior A+P mechanic in the States somewhere as they have the perfect job for you. Ignorance is bliss.

 

and in case you guys do not have the proper tie down equiment, i'll keep that in mind the next time a starflex comes in for warranty due to cracking after a few hundred hours. Who's responsible if the blades aren't being tied down correctly in the first place?

[Lunchbox]

Starflex cracking with less than 100 hrs TSN. Unless this is a common occurance for this particular operator, couldn't there be a possibility of improper manufacture of the starflex installed?

[PerfectTrack]

there always is that possibility. read my other posts regarding the steps in the non destructive testing that it goes through (all it takes is one test to find a manufacturing delamination or poor bond, and they all get checked) and then tell me the rate at which errors can occur on the field level that would contribute to cracking. Lets compare.

 

I look at the picture supplied, which i assume is the gulf operator, and i see the amount of splintering running spanwise though the arm, this was not suddenly there during a quick run-up (not even past ground idle) and then shut down. that star arm had to have been cracked, bad enough to at least be seen visually on a DI. There was more forces at play over time.

 

Lets ask the maintenance guys who performed the install of the starflex....we all know that starflex gets warped awefully bad when you pin that first blade in place. (did they go for coffee after hanging the first blade?) after the second, it's still off kilter. Once the third blade gets pinned it levels off and the droop ring is now evenly carrying the load of all three blades. So who's willing to rule out all the possibilities at this point? The story still has alot of voids, no pun intended.