89-20-02: Tail Rotor Hubs

89-20-02 MCDONNELL DOUGLAS HELICOPTER COMPANY (MDHC): Amendment 39-6324. (Docket No. 89-ASW-32) Applicability: Model 369D and E helicopters, certificated in any category, with hubs of four-bladed tail rotors, Part Number (P/N) 369D21700-3 installed. Compliance: Required as indicated, unless already accomplished. To prevent fatigue failure of four-bladed tail rotor hubs which could result in loss of control of the helicopter, accomplish the following: (a) Within 10 hours' time in service after the effective date of this AD, remove each tail rotor hub, (P/N) 369D21700-3, with serial numbers 196 through 251, installed on a helicopter and visually inspect for electrical arc burns and dye penetrant inspect for cracks. If arcing burns or cracks are observed as a result of this inspection, replace the hub with a serviceable unit prior to further flight. NOTE: McDonnell Douglas Helicopter Company Service Information Notices DN-160 and EN-50 pertain to this inspection. (b) Within 100 hours' time in service after the effective date of this AD, remove each tail rotor hub, (P/N) 369D21700-3, with serial numbers from 1 through 195, and visually inspect for electrical arc burns and dye penetrant inspect for cracks. If arc burns or cracks are observed as a result of this inspection, replace the hub with a serviceable unit prior to further flight. (c) Prior to installation in a helicopter, visually inspect each four-bladed tail rotor hub, (P/N) 369D21700-3, serial numbers 1 through 251, in spares inventory for electrical arc burns and dye penetrant inspect for cracks. If arc burns or cracks are observed as a result of this inspection, reject the hub. (d) Enter the results of the above inspections required by paragraphs (a) and (b) in the aircraft log and report cracks or arc burns to the Los Angeles FAA Aircraft Certification Office within 10 days of the inspection. Include in the report the helicopter model and serial number, hub part number, hub serial number, vendor identification (if possible), total hours of service for the hub, the location of any cracks and arc burns, and the geographical location (city, state) of the helicopter at the time of inspection. (e) Report the results of the inspections of paragraph (c) on hub spares, when arc burns or cracks are found, to the Los Angeles FAA Aircraft Certification Office within 10 days of the inspection. Include the date of the inspection, hub part number, hub serial number, vendor identification (if possible), total hours in service (if previously used, or zero hours if new), the location of arc burns and/or cracks, and the geographical location of the inspection. NOTE: All new hubs (zero service life) which are rejected should be returned to MDHC for further inspection and evaluation. (f) The reporting requirements of this regulation have been approved by the Office of Management and Budget under OMB No. 2120-0056. (g) In accordance with FAR Sections 21.197 and 21.199, the helicopter may be flown to a base where compliance with the AD may be accomplished. (h) An alternate method of compliance with this AD which provides an equivalent level of safety may be used if approved by the Manager, Los Angeles Aircraft Certification Office, FAA, 3229 E. Spring Street, Long Beach, California. This amendment (39-6324, AD 89-20-02) becomes effective on October 16, 1989.