Rotor blade skin debonding

FAA Aircraft Certification Service SPECIAL AIRWORTHINESS INFORMATION BULLETIN http://www.faa.gov/aircraft/safety/alerts/SAIB

SAIB: SW-07-16 DATE: February 9, 2007 This is information only. Recommendations aren’t mandatory.

Introduction

This Special Airworthiness Information Bulletin (SAIB) alerts owners and operators of Robinson Helicopter Company models R22 and R44 that the rotor blade skin may begin to debond at the skin- to-spar joint on the lower surface at the tip. The Robinson Helicopter Company has issued a safety alert warning of this condition. It is available on the company web site at www.robinsonheli.com. This SAIB applies to all R22, R22 Alpha, R22 Beta, R22 Mariner, R44, and R44 II helicopters with main rotor blades part number A016-4, C016-2 or C016-5.

Background

Four R22 A016-4 blades skins have been found debonded at the outboard tip lower surface where the skin butts up against the spar. Six similar debonds have occurred on R44 blades, part number C016-2. The debond can occur when either the paint is eroded enough to expose the leading edge of the lower skin, or if corrosion is present at the blade tip. Preflight inspection of this area should allow early detection of a debond and prevent a catastrophic failure.

Recommendation

During daily preflight inspections carefully inspect the lower skin-to-spar joint area, especially the outboard 10 inches (See Robinson Safety Alert dated 04 January 2007 for the location). If any area of the skin is not flush with the spar, the blade should be considered un-airworthy. On blades with paint still covering the skin-to-spar joint, a crack in the paint may indicate a debond. If any indication of a debond is detected, a “tap test” by a qualified mechanic should be performed prior to further flight to detect an actual disbond. If any indication of a debond is detected, the blade should be considered un- airworthy.

If unusual rotor system noise or vibration is detected in flight, land immediately and inspect blades.

For Further Information Contact

Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California 90712

For R22:

Mr. Eric Schrieber, Aerospace Engineer; phone: (562) 627-5348; fax: (562) 627-5210 email: [email protected]

For R44:

Mr. Fred Guerin, Aerospace Engineer; phone: (562) 627-5232; fax: (562) 627-5210 email: [email protected]