DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39 

[Docket No. 89-ASW-10; Amendment 39-6456, AD 90-01-08] 

Airworthiness Directives; McDonnell Douglas Helicopter Co. Model 369 series helicopters (including Models YOH-6A and OH-6A) Helicopters.

AGENCY: Federal Aviation Administration (FAA), DOT. 

ACTION: Final rule.  

DATES: Effective February 5, 1990.

90-01-08   MCDONNELL DOUGLAS HELICOPTER COMPANY (MDHC): 
	Amendment 39-6456.   Docket No. 89-ASW-10. 
	Applicability:   Model 369 series helicopters (including Models YOH-6A and OH-6A) certificated in any category. 
	Compliance:   Required as indicated, unless already accomplished. 
	To prevent possible failure of the engine-to-transmission driveshaft coupling, which could result in loss of control of the helicopter, accomplish the following: 
	(a)   Within the next 25 hours' time in service or within 120 days after the effective date of the AD, whichever occurs first, inspect the couplings, MDHC Part-Number (P/N) 369H5660, to determine serial numbers. 
	(b)   Replace any couplings, P/N 369H5660, which have serial numbers in the range from 5200 through 5309, with airworthy parts. 
	(c)   Record compliance with paragraph (a) of this AD in the AD compliance record and in the maintenance record of the helicopter log book.   This record must include the serial numbers of any deficient couplings found during compliance with this AD. 

	NOTE:   MDHC Service Information Notices HN-216, DN-157, EN-47, FN-35, dated April 5, 1989, pertain to this subject. 

	(d)   In accordance with FAR Sections 21.197 and 21.199, flight is permitted to a base where the requirements of this AD may be accomplished. 
	(e)   An alternate method of compliance or adjustment of the compliance time which provides an equivalent level of safety, may be used if approved by the Manager, Los Angeles Aircraft Certification Office, ANM-100L, FAA, 3229 East Spring Street, Long Beach, California 90806-2425. 

	NOTE:   Unairworthy couplings removed from service and in spares inventory should be marked unairworthy.   Unairworthy couplings should be purged from spares inventory in accordance with MDHC SIN HN-216, DN-157, EN-47, FN-35, dated April 5, 1989. 

	This amendment (39-6456, AD 90-01-08) becomes effective on February 5, 1990. 

FOR FURTHER INFORMATION CONTACT:  Mr. Roy McKinnon, Aerospace Engineer, ANM-143L, FAA, Northwest Mountain Region, Los Angeles Aircraft Certification Office, 3229 East Spring Street, Long Beach, California 90806-2425; telephone (213) 988-5247.