91-06-13 BRITISH AEROSPACE: Amendment 39-6930. Docket No. 90-NM-258-AD.
Applicability: Model ATP series airplanes equipped with main wheel assemblies, Part Number AHA1538 and AHA1663, certificated in any category.
Compliance: Required as indicated, unless previously accomplished.
To prevent seizure of the main landing gear (MLG) wheel and subsequent damage to the tire, accomplish the following:
A. Within 30 days after the effective date of this AD, and thereafter at each wheel removal, on each wheel of the left and right main landing gear, perform a visual inspection of the wheel hub halves and wheel bearing grease retainer seals, in accordance with British Aerospace Service Bulletin ATP-32-13, Revision 1, dated February 28, 1990.
NOTE: The British Aerospace service bulletin references Dunlop Limited Service Bulletin 32-1032, Revision 1, dated February 13, 1990, for additional instructions.
1. Measure the diameter of the grease retainer seal locating groove for wear on the brake side half hub.
a. If the diameter of the groove exceeds 4.540 inches, prior to further flight, replace with a serviceable part, in accordance with Dunlop Limited Service Bulletin 32-1032, Revision 1, dated February 13, 1990.
b. If the diameter of the groove does not exceed 4.540 inches, prior to further flight, protect the bore of the hub half with an application of Alocrom, in accordance with the Dunlop Limited service bulletin.
2. Verify that the brake side grease retainer seal, Part Number AH089109, has the cross-section shown in Figure 2 of Dunlop Limited Service Bulletin 32-1032, Revision 1, dated February 13, 1990. If this part's configuration is different (has not been chamfered), prior to further flight, replace it with a modified Part Number AH089109, in accordance with the Dunlop Limited service bulletin.
3. Visually inspect the inner bore and outer circumference of brake side grease retainer seal, Part Number AH089109. If the external circumference and the internal bore of the grease retainer seal, Part Number AHO89109, is scored or chipped, prior to further flight, replace it with a serviceable part in accordance with the Dunlop Limited service bulletin.
4. Verify that the valve side grease retainer seal is marked as Part Number AHO89720. Prior to further flight, replace any grease retainer seals not marked Part Number AHO89720 with one so marked.
5. Visually inspect the valve side grease retainer seal, Part Number AH089720. If the internal bore and the wheel bearing face of the grease retainer seal show signs of wear, prior to further flight, replace all defective grease retainer seals in accordance with the Dunlop Limited service bulletin.
B. Accomplishment of Dunlop Modification C2614, which consists of installing improved grease retainer seals on both the brake side and the valve side half hubs, in accordance with Dunlop Limited Service Bulletin AHA1538/AHA1663-32-1042, dated April 10, 1990, constitutes terminating action for the repetitive inspections required by paragraph A. of this AD.
C. An alternate means of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate.
NOTE: The request should be submitted directly to the Manager, Standardization Branch, ANM-113, and a copy sent to the cognizant FAA Principal Inspector (PI). The PI will then forward comments or concurrence to the Manager, Standardization Branch, ANM-113.
D. Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD.
All persons affected by this directive who have not already received the appropriate service documents from the manufacturer may obtain copies upon request to British Aerospace, PLC, Librarian for Service Bulletins, P.O. Box 17414, Dulles International Airport, Washington, D.C. 20041-0414. These documents may be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 1601 Lind Avenue S.W., Renton, Washington.
This amendment (39-6930, AD 91-06-13) becomes effective on April 15, 1991.