AD 98-15-26 Airworthiness Directives; McDonnell Douglas Helicopter Systems Model 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, 600N, and OH-6A Helicopters

Models named: 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N. Read the applicability below — it usually turns on serial or part numbers too.

Model 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, 600N, and OH-6A helicopters with main rotor blades Part Number (P/N) 369A1100-507 with Serial Number (S/N) D139 through D203, D209 through D223; P/N 369D21100-517 with S/N H664, H665, H667, H669, H671, H672, H674, H676, H679, H680, H683 through H724, H726 through H999, J000 through J039, J041 through J055; or P/ N 369D21102-517 with S/N 1976 through 2100, 2106 through 2115, 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 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 use the authority provided in paragraph (f) to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition, or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alternation, or repair remove any helicopter from the applicability of this AD.

Required as indicated, unless accomplished previously. (a) For Model 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, and OH-6A helicopters with any affected main rotor blade (blade) that has 600 or more hours time-in-service (TIS), to detect cracks that could lead to failure of the blade and subsequent loss of control of the helicopter, before further flight and thereafter at intervals not to exceed 25 hours TIS, accomplish the following: (1) With each blade lifted off the droop stop, using a 10X or higher magnifying glass, visually inspect the blade for any chordwise cracking starting at the root fitting edge on the blade lower surface doubler and skin or cracks on the doubler adjacent to the root end fitting (Figure 1). If any cracking is discovered, remove the blade and replace it with an airworthy blade. Note 2: Boeing McDonnell Douglas Helicopter Systems Service Bulletin No. SB369H-243R3, SB369E-088R3, SB500N-015R3, SB369D-195R3, SB369F-075R3, SB600N-007R2, dated July 13, 1998 (SB), pertains to the subject of this AD. (2) With each blade lifted off the droop stop, inspect the lower surface for missing or cracked adhesive or paint at the root end fitting-to-doubler bond line (Figure 1). If any missing or cracked adhesive or paint is discovered, remove and inspect the blade in accordance with paragraph 3E of Part II of the Accomplishment Instructions in McDonnell Douglas Helicopter Systems Service Information Notice No. HN-239, DN-188, EN-81, FN-67, NN-008, dated October 27, 1995. If there is any disbonding in excess of the allowable margins specified in paragraph 3E of Part II of the service information notice, replace the blade with an airworthy blade. BILLING CODE 4910-13-M [[Page 39495]] [GRAPHIC] [TIFF OMITTED] TR23JY98.000 BILLING CODE 4910-13-C [[Page 39496]] (b) For the Model 600N helicopters, before further flight, remove any affected blade from service and replace it with an airworthy blade not listed in the applicability section of this AD. Blades removed from the Model 600N helicopters are not eligible for use on any rotorcraft. Note 3: The recurring inspection requirements, contained in paragraph (a) of this AD, DO NOT apply to the Model 600N helicopters. (c) Affected blades are to be removed from service on or before reaching either of the applicable new life limits. The new life limits are determined by hours TIS or number of torque events (TE). A torque event is defined as the transition to a hover from forward flight. For this definition of TE, forward flight is considered to be flight at any airspeed after attaining translational lift. (1) For blades that do not have TE logged, prior to further flight, log the TE in the rotorcraft log or equivalent record as follows: (i) Log the number of TE, if known. (ii) For noncargo hook operations, if the number of TE is unknown, log 6 TE for each hour TIS. (iii) For cargo hook (external load) operations, or for any combination of noncargo hook operations and cargo hook (external load) operations, if the number of TE is unknown, log 20 TE for each hour TIS. (2) Make any entry into the component record or equivalent record to reflect new life limits for blade P/N's as follows: (i) For P/N 369A1100-507, Models 369A, 369H, 369HE, 369HM, 369HS, and OH-6A, enter 1,750 hours TIS or 10,600 TE, whichever occurs first. (ii) For P/N 369D21100-517, Models 369D and 369E, enter 2,500 hours TIS or 15,000 TE, whichever occurs first. (iii) For P/N 369D21102-517, Model 369F, 369FF, and 500N, enter 2,500 hours TIS or 15,000 TE, whichever occurs first. (d) After compliance with paragraph (c) of this AD, during each operation thereafter, maintain a count of TE performed and additional hours TIS accumulated, and, at the end of each day's operations, add those counts to the accumulated number of TE and hours TIS on the rotorcraft log or equivalent record. (e) The blades are no longer retired based upon only hours TIS. This AD revises the Airworthiness Limitations Section of the maintenance manual by establishing a new retirement life for certain blade P/N's based on hours TIS or a number of TE, whichever occurs first. (f) 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 4: 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. (g) Special flight permits will not be issued. (h) The inspection required by paragraph (a)(2) of this AD shall be done in accordance with McDonnell Douglas Helicopter Systems Service Information Notice No. HN-239, DN-188, EN-81, FN-67, NN-008, dated October 27, 1995. This incorporation by reference was approved previously by the Director of the Federal Register as of May 29, 1996 (61 FR 24220, May 14, 1996). Copies may obtained from McDonnell Douglas Helicopter Systems, Commercial Technical Publications, Bldg. M615/G048, 5000 E. McDowell Road, Mesa, Arizona 85215-9797, telephone 602-891-3667, fax 602-891-6522. Copies may be examined at the FAA, Office of the Regional Counsel, Southwest Region, 2601 Meachum Blvd., Room 663, Fort Worth, Texas, or at the Office of the Federal Register, 800 North Capital Street NW., suite 700, Washington, DC. (i) This amendment becomes effective on August 3, 1998. Issued in Fort Worth, Texas, on July 17, 1998. Henry A. Armstrong, Manager, Rotorcraft Directorate, Aircraft Certification Service. [FR Doc. 98-19615 Filed 7-22-98; 8:45 am] BILLING CODE 4910-13-M