Composite Blade Repair

Turbine Technology

“We put the blade inside a vacuum bag, to eliminate any bubbles and ensure a really tight fit,” says Spoltman. “In either case, the adhesive cures in 12 hours at room temperature; two to three hours at 140 F to 150 F.”

Once the new leading edge is properly bonded to the composite blade, the unit is sanded until it matches the original spec, then painted.

When to do it yourself, and when not to
With customers always wanting their aircraft back in service yesterday, and financial pressures being what they are, it makes sense for aircraft maintenance shops to do as many repairs themselves as possible, rather than sending parts back to the manufacturer. So how do you know when you can do the work yourself and when you can’t?

“There are three levels of composite blade repairs,” says Spoltman. “These are classified as minor, major, and factory-only repair procedures.”

A minor repair is one that most qualified AMTs can do themselves. These are minor nicks that don’t require much material replacement, and cover the vast majority of repairs performed.
“Once you sand the area and apply the fiberglass, you just have to ensure that there are no areas of delamination or bubbles,” says Spoltman.

A major repair occurs when the nick is significant — something that is more than superficial, in other words.

“These are the kinds of repairs that require a vacuum pump to ensure proper lamination, and should only be done by authorized repair stations,” says Spoltman. “At the factory-only level comes substantial blade damage, including damage caused by the prop hitting the ground. For these repairs, we rebuild the composite blade using a mold that ensures the prop conforms to its specified shape and dimensions.”

A word to the wise
The idea of repairing an advanced composite blade may intimidate veteran AMTs accustomed to wooden and metal props. But there’s no need for fear.

“The technique for fixing composite blades is pretty straightforward,” says Spoltman. “You just have to be thorough. The worst thing you can do is rush through the inspection process, missing damage that needs to be fixed. Be methodical and chances are that you won’t have any problems.”

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