UK & Oz R-44 operators. Are you aware of this?
SUPPLEMENTARY INFORMATION: On March 26, 1999, the FAA issued Priority Letter AD 99-07-18, applicable to RHC Model R44 helicopters, which requires, before further flight, inserting a Special Pilot Caution into the Normal Procedures section of the RFM. That action was prompted by several reports of sprag clutch assemblies, including one from wreckage of an accident that occurred within the past year, with cracked or fractured sprag ends. The sprag clutch failures, determined to be due to a change in the manufacturing process, could result in loss of main rotor RPM during autorotations. The intent of that priority letter AD is to alert pilots of the potential for the sprag clutch failing to overrun during autorotation, loss of main rotor RPM, and subsequent loss of control of the helicopter.
The FAA has reviewed Robinson Helicopter Company R44 Service Bulletin SB-32, dated March 22, 1999, which describes procedures for checking whether sprag clutches with certain serial numbers are installed and replacing certain serial numbered sprag clutches, and inserting a Special Pilot Caution in the Normal Procedures section of the RFM.
Since the unsafe condition described is likely to exist or develop on other RHC Model R44 helicopters of the same type design, the FAA issued Priority Letter AD 99-07-18 to alert pilots of the potential for the sprag clutch failing to overrun during autorotation due to the failure of the sprags within the sprag clutch assembly and loss of main rotor RPM. The AD requires, before further flight, inserting a Special Pilot Caution into the Normal Procedures section of the RFM which primarily addresses autorotation maneuvers and a before every flight sprag clutch (split tach needles) check for proper function of the sprag clutch. Inserting the Special Pilot Caution is an interim action. The FAA will issue an AD to supersede this AD and require replacing the clutch assembly when parts become available from the manufacturer. The short compliance time involved is required because the previously described critical unsafe condition can adversely affect the structural integrity of the helicopter. Therefore, inserting a Special Pilot Caution into the Normal Procedures section of the RFM is required before further flight, and this AD must be issued immediately.
Since it was found that immediate corrective action was required, notice and opportunity for prior public comment thereon were impracticable and contrary to the public interest, and good cause existed to make the AD effective immediately by individual letters issued on March 26, 1999, to all known U.S. owners and operators of RHC Model R44 helicopters. These conditions still exist, and the AD is hereby published in the Federal Register as an amendment to section 39.13 of the Federal Aviation Regulations (14 CFR 39.13) to make it effective to all persons.
The FAA estimates that 200 helicopters of U.S. registry will be affected by this AD, that it will take approximately 0.5 work hour per helicopter to insert the caution into the RFM, and that the average labor rate is $60 per work hour. Based on these figures,