Airwolf combats Robinson helicopter blade delamination
July 19, 2011, Middlefield, Oh. - Airwolf Aerospace LLC. is marketing its FAA-certified (STC) blade tape kits as a protective measure against blade skin delamination on Robinson R22 and R44 helicopter main rotor blades.
By Carey Fredericks
The FAA recently issued a second Airworthiness Directive (AD 2011-12-10) on all Robinson helicopters.
In 2007, Robinson Helicopter Co. issued service alerts SB-72 and SB-103 advising owners that some main rotor blade skins were prone to debonding at the skin-to-spar joint on the lower surface of the blade tips, causing the aircraft to compromise its airworthiness. Debonding can occur when the bond line is exposed due to excessive erosion of the blade finish, or when corrosion occurs on the internal aluminium tip cap.
This most recent AD revisits a 2007 directive, which instructs Robinson R22 and R44 operators to inspect main-rotor blades for possible defects before each flight. Airwolf addressed this through its Alternative Method Of Compliance (AMOC), a certified blade tape that overlaps the skin and leading edge, obviating the need for recurrent inspections and lap-joint painting.
Airwolf Aerospace Senior Engineer, John Montana said, “ The problem of delamination can be largely avoided if owners install our easy-to-apply blade tapes, protecting the joint in question. We look at our tapes as an effective form of insurance against having to buy new blades which can cost between $25,000 and $40,000.”
Airwolf’s solution, STC- SR02491CH, uses a proprietary polymer tape which is bonded to the blade. This prevents the leading-edge skin debonding, which occurs when the bond line is exposed due to erosion of the blade’s painted finish. The blade tape covers the outboard section of the rotor blade where history has shown debonding to occur. It seals the bond line making penetration by foreign objects impossible, and drastically reduces the risk of blade skin delamination.
“Pre-flight blade inspections required by the A.D. are now a breeze as all the pilot has to do is look up and see the blade tape is still covering the bond line.. It is a great solution to a problem that affects more than 3,000 helicopters in the US alone,” adds Montana.
Working with 3M, Airwolf modified 3M’s tape that was originally designed for use on CH-47 Chinook and S-70 Blackhawk helicopters, to make it compatible for the smaller, narrower Robinson rotor blade. Applied as per Airwolf’s detailed instructions, the tape prevents delamination without causing any loss in aerodynamic performance.
The current price of the rotor blade protective kit is $1299 for the R22 and $2499 for the R44. Once the initial kit and STC has been purchased, Airwolf offers blade tape repair kits costing $500 for the R22 and $1000 for the R44.