AWB 63-3 Issue 1, Robinson R44

Applicability: Robinson R44 Lower Actuator Bearing Mounting Bracket

Purpose: Advise operators and maintainers of R44 helicopters of the potential of unanticipated loss of power to the rotor, resulting in a forced autorotative landing and with the additional possibility of the engine exceeding design RPM.

Background: Routine maintenance discovered an extensive crack in the mounting bracket.

This bracket is a vital part of the R44 drive train from the engine to the rotor. If this bracket should fail, main drive belt tension would be lost almost immediately. This would result in a forced autorotative landing. At the same time, because the engine would be suddenly disconnected from the drive train while running at almost full power, the engine may well exceed design RPM.

The R22 has an almost identical lower actuator bearing mounting bracket arrangement to the R44. Robinson Service Bulletin No. 144, and CASA AD/R22/24 directs the maintainer to inspect the R22 for loose rivets in this bracket every 50 hours. There is currently no similar direction for the R44, and integrity checks on this bracket rely on the person doing the inspection in this area including the lower actuator bearing mounting bracket as part of the inspection of the scroll.

Recommendation: CASA recommends that people maintaining the R44 pay critical attention to this bracket during routine maintenance inspection of the scroll, and ensure any damaged brackets are replaced, and that any minor damage to the edges at the ends of the bracket are removed in an approved manner. All instances of cracking in this bracket should be reported immediately to CASA.

FMI: www.casa.gov.au/avreg/aircraft/AWB/63/003.htm