INFORMATION LETTER #2005-1
Media Blasting of Paint on Sikorsky Rotor Blades
In recent years media blasting of aircraft parts to remove old paint has become an ever-increasing method as a substitute for chemical paint stripping.
Should you wish to investigate this method, please be aware of the potential consequences.
First, you should look into the OEM's specs and procedures for the process and approval of which parts are approved for media blast paint removal. At this time, Sikorsky does not approve of any media blast system for use on its metal rotor blades.
Second, if no OEM specs, and you are determined to use a media blast system, be very careful. Use of media equipment in the inexperienced hands can have serious and costly consequences. Please look at the enclosed pic's as to what can happen. The person who caused this damage probably thought he was being careful. He was terribly wrong.
The two S-61 blades shown below were media blasted by an inexperienced and unaware individual who cost his owner in excess of $22,000.00us for pocket replacement repairs. The pocket skin on both main rotor and tail rotor blade is made from .012” aluminum material. By aggressively blasting in 1 area to long the material will stretch between the ribs giving you this undesirable look and an unserviceable rotor blade.
Third, the owner/operator also needs to review whether or not their repair station authorization extends to cover rotor blade type of repairs. Rotor blades are not lumped in with blanket component type authorities. You or your employees, could in fact be opening the company up to a liability you had not thought of.
One more thing to consider, The reason Sikorsky does not allow entire rotor blade paint stripping and repainting in either the Maintenance Manual or the Structural Repair Manual, (please check for yourself) is because the owner/operator does not have the proper authorizations/balance equipment/procedures/tooling/personnel to completely strip, repair, refinish and rebalance the blade back to a known master. The balancing of the blade is as critical to a rotor blade as the gear setting is to a gearbox. Sikorsky only allows touch up type of repairs to the painted surface.
This letter is intended to bring a potential problem to the attention of the owner/operator, before someone has a real bad day, thereby reducing your costs and possible FAA discrepancy issues.
Please call ABS at 407-846-6780 if you should have any questions or concerns.
Leonard Peterson, President
David Stutesman, Vice-President