Robinson R44 Service Bulletin SB-108 also became an Airworthiness Directive (FAA AD 2021-19-8)

The FAA has received reports of cracks found along the leading edge of the tail rotor blades of part number (P/N) C029-3, serial numbers (S/N) 9410 through 9909. The tail rotor blades in question were either factory installed or shipped as replacement parts between March and December 2019. The cracks were detected at various intervals, from pre-flight inspections to 100-hour inspections. In one case, a cracked blade was suspected when the pilot felt an abnormal vibration during flight, which was later confirmed by investigation. The cracks are attributed to a manufacturing defect in the blade skin properties that causes the blades to be susceptible to stress corrosion cracking. If the problem is not corrected, it could result in reduced controllability and subsequent loss of control of the helicopter. The FAA has issued an AD to correct the unsafe condition of these products.

Robinson Helicopter Company Service Bulletin R44 SB-108, dated June 30, 2021, specifies that blades P/N C029-3 with serial numbers 9410 through 9909 be removed from service no later than December 31, 2021. To ensure uninterrupted service until the blades are replaced, the service bulletin specifies a pre-flight inspection to be performed by the pilot. Due to the problem, and if several conditions are met, the list price of the blade ($3,320) is being reduced to $940.

The FAA AD also requires, before further flight, and before each subsequent flight, that blades P/N C029-3 with S/Ns 9410 through 9909, inclusive, be inspected for any cracks along the leading edge of the blade. The owner/operator (pilot) may perform the required inspection, but must record compliance with the appropriate paragraph of this AD in the helicopter maintenance records. The pilot may perform this inspection, as it involves visually inspecting each blade for cracks. This action may be performed equally well by a mechanic. This inspection is an exception to the standard FAA maintenance regulations. The AD also requires, before further flight, that any cracked blades be removed from service and that blades with these serial numbers not be installed in any helicopter. In addition, the AD requires, within three months of the effective date of the AD (September 22, 2021), that all blades with these serial numbers be removed from service.