Robinson Helicopter’s R22 and R44 models main rotor blade delaminations have become the subject of a FAA Airworthiness Directive
Robinson Helicopter’s R22 and R44 models main rotor blade delaminations have become the subject of Federal Aviation Administration’s (FAA) Airworthiness Directive (AD) 2007-26-12, superseding the Company’s Service Bulletin.
The AD states that main rotor blade skins begin to delaminate, debond, or separate the ski near the blade tip. This delamination or debonding can occur when the bond line is exposed due to excessive erosion of the blade finish, or when corrosion occurs on the internal aluminum tip cap. Furthermore, it is important to keep in mind that the blades are matched and balanced at the factory. This implies that if one blade is due for maintenance or replacement, it is likely the opposite blade will also need the same attention.
The FAA estimates that this AD will affect 2290 helicopters registered in the United States. The Robinson Helicopter Company which is based in Torrance CA, has built and sold over, 8,000 Helicopters globally. Logically, these 8000 R44 and R22 copters are or would be due for inspection, repair and/or replacement.
Robinson Helicopter Company had previously issued Service Bulletins to to R44 and R22 owners, warning them to inspect and address the problem using repeat-as-necessary paint applied to the affected areas of the main rotor blades. The issuance of this AD elevates significantly the gravity and immediacy of the situation for all R22 and R44 owners and operators. Owners and operators of these Robinson helicopters must now perform a daily visual inspection of each blade, before flight.
Outside companies such as Airwolf Aerospace LLC, have developed processes which they claim to do a better job in preventing the debonding and delaminations. Air wolf developed an epoxy tape application process to prevent the debonding of the stainless steel main rotor blades on Robinson Helicopter R22 and R44 models. Airwolf says that some 300 Robinson owners and operators have purchased their fix.
The epoxy tape used by Airwolf is four inches wide and is installed on the outer 36 inches of the 12.5-foot R22 blades and the outer 38 inches of the slightly longer R44 blades. A company spokesman claimed that there is no performance change in the operation of either model helicopter and no flight manual supplement is required following installation. He also stated there also is no concern about the tape coming off after application. “Once it’s on there it’s not coming off,” he said. The tape protects the adhesive bond that holds the rotor blade skin to the rest of the structure, protecting it from dust particles and moisture. Noting that the cost of the Airwolf tape repair is only a fraction of the cost of buying new rotor blades, Kochy said, “It’s in your best interest to protect those blades. This is just cheap insurance to keep [debonding] from happening,” Kochy said, adding that there is “a misunderstanding of the severity” of the problem among Robinson owners and operators. Helicopters Magazine.
Aviation Week Magazine reported, “The stainless steel blades on both models of Robinson helicopters have a stated service life of 2,200 hours time in service. The NTSB said that FAA should require nondestructive testing of all Robinson rotor blades “at intervals appropriately less than 596 hours time in service…to evaluate the bond joints between the skin and spar at the tip of the main rotor blade…” This was following the NTSB’s investigation of a number of main rotor blade delamination accidents of R44 and R22 helicopters.
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