AD 2002-22-51 Airworthiness Directives; MD Helicopters, Inc. Model MD900 Helicopters

MD-900 helicopters, serial numbers 900-00008 through 900-00110, with a main rotor support static mast (mast), part number 900F2401021-101, installed, certificated in any category. Note 1: This AD applies to each helicopter identified in the preceding applicability provision, regardless of whether it has been otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For helicopters that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (d) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Required before further flight, unless accomplished previously. To detect cracks and pitting in the mast that could result in failure of the mast, separation of the main rotor, and subsequent loss of control of the helicopter, accomplish the following: (a) Remove the main rotor drive shaft. Note 2: MD Helicopters, Inc. Service Bulletin No. SB900-089R1, dated October 22, 2002, pertains to the subject of this AD and has a Figure 1 depicting the inspection areas of the mast. (b) Remove 1 inch of primer from the top inside diameter of the mast. During paint removal, wipe the area clean. Do not scrub or flush the area. Do not allow paint stripper to run down the inside or outside surfaces of the mast below the work area or enter into the transmission. Inspect the top 1 inch of the inside diameter of the mast for a crack or pitting using a bright light and a 10x or higher magnifying glass. If you find any crack or pitting, remove the mast from service. (c) Remove the main rotor hub assembly. Clean the threads of the mast thoroughly with solvent. Inspect the mast threads for a crack using a bright light and a 20x or higher magnifying glass. Pay particular attention to the thread root area. If you see a flaw in the thread area and cannot determine if it is a crack, perform a magnetic particle inspection (wet fluorescent) per ASTM E 1444-01 using an electromagnetic yoke or coil. If you find any crack or pitting, remove the mast from service. (d) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Los Angeles Aircraft Certification Office, FAA. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Los Angeles Aircraft Certification Office. Note 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles Aircraft Certification Office. (e) Special flight permits will not be issued. (f) This amendment becomes effective on December 26, 2002, to all persons except those persons to whom it was made immediately effective by Emergency AD 2002-22-51, issued October 23, 2002, which contained the requirements of this amendment. Issued in Fort Worth, Texas, on November 25, 2002. Eric Bries, Acting Manager, Rotorcraft Directorate, Aircraft Certification Service. [FR Doc. 02-31176 Filed 12-10-02; 8:45 am] BILLING CODE 4910-13-P