Airworthiness Directive · Amendment 39-14569 · MD Helicopters, Inc. Model 600N Helicopters
MD Helicopters, Inc. Model 600N Helicopters
Superseded. A later AD replaced this one: AD 2008-05-17, AD 2008-20-05. Comply with the one in force.
Model 600N helicopters, serial numbers with a prefix “RN” and 003 through 058, that have not been modified in the fuselage aft section to strengthen the tailboom attachments and longerons in accordance with MD Helicopters Technical Bulletin TB600N-007, dated January 12, 2004, or TB600N-007, Revision 1, dated April 13, 2006, certificated in any category.
This amendment supersedes an existing airworthiness directive (AD) for the MD Helicopters, Inc. (MDHI) Model 600N helicopters, that currently requires inspecting both upper tailboom attachment fittings, nut plates and both angles for a crack or thread damage, and repairing or replacing any cracked or damaged part. That AD also requires replacing the upper right tailboom attachment bolt with a new attachment bolt, and if the upper right attachment bolt is broken, replacing the three remaining attachment bolts with airworthy bolts. Adding a washer to each bolt and modifying both access covers is also required. Thereafter, inspecting the upper tailboom attachments and repairing or replacing any cracked part is required by that AD. That AD was prompted by the discovery of a cracked attachment bolt on a helicopter. This AD requires those same actions, plus installing additional inspection holes in the aft fuselage skin panels and inspecting the upper and lower tailboom attachment fittings, the upper longerons, and the angles and nut plates for cracks. It also requires, within a specified time, replacing the upper right tailboom attachment fitting, painting the inspection area, and replacing existing nut plates. Additionally, it requires inspecting the attachment bolts for any damage or wear. This amendment is prompted by an accident involving a Model 600N helicopter. The actions specified by this AD are intended to prevent failure of the tailboom attachment fittings, separation of the tailboom from the helicopter, and subsequent loss of control of the helicopter.
Required as indicated.
To prevent failure of the tailboom attachment fittings, separation of the tailboom from the helicopter, and subsequent loss of control of the helicopter, accomplish the following:
Note 1: There is a slight discrepancy between MD Helicopters, Inc. Service Bulletin SB600N-036, dated November 2, 2001 (SB600N-036) and MD Helicopters Service Bulletin SB600N-039, dated December 9, 2003 (SB600N-039) on the vertical location of the upper left inspection hole. Either location is acceptable for this AD.
(a) Within 5 hours time-in-service (TIS), unless accomplished previously:
(1) Remove the tailboom fairing and tailboom. Remove both upper tailboom attachment access covers in accordance with the Accomplishment Instructions, paragraph 2.B.(2) of SB600N-036.
Note 2: MDHI CSP-HMI-2, Section 53-40-30, pertains to the subject of this AD.
(2) Using a light and a 10x or higher magnifying glass:
(i) Inspect the right and left upper tailboom attachment fittings, part number (P/N) 500N3422 and 500N3422-3, respectively, for a crack as shown in Figure 1 of the SB600N-036. If a crack is found, replace any cracked attachment fitting with an airworthy attachment fitting before further flight.
(ii) Inspect both upper tailboom attachment nut plates for thread damage or a crack. Replace any damaged or cracked nut plate with an airworthy nut plate before further flight.
(iii) Inspect both angles for a crack. If a crack is found on a right-hand angle, P/N 500N3429-6, before further flight, install a new clip in accordance with the Accomplishment Instructions, paragraph 2.B.(5)(c) of the SB600N-036. If a crack is found on the left-hand angle, P/N 500N3429-7, before further flight, replace the angle with an airworthy angle, or repair the angle in accordance with FAA-approved procedures.
(3) Replace the upper right (pilot side) tailboom attachment bolt (bolt) with a new bolt.
(4) If the removed upper right pilot-side bolt is broken, replace the remaining three bolts with airworthy bolts before further flight.
(5) Add one washer, P/N AN960C516 (NAS1149C0563R) or AN960C616 (NAS1149C0663R), as appropriate, to each tailboom bolt between the tailboom and the NAS1587 countersunk washer. A minimum of two threads must extend past the nut plate.
(6) Modify both access covers in accordance with the Accomplishment Instructions, paragraph 2.B.(6), of the SB600N-036.
(b) Within 5 hours TIS, unless accomplished previously:
(1) Drill four additional inspection holes in the fuselage as shown for the left side of the fuselage in Figure 1 of SB600N-039, by following the Accomplishment Instruction paragraphs of SB600N-039 as follows:
(i) Paragraphs 2.A.(1)(a), (b), and (d) for inspection holes at L166 and R166.
(ii) Paragraphs 2.A.(2)(a), (b), and (d) for inspection holes at L153 and R153.
(2) Thoroughly clean the attachment fittings and surrounding area. If the attachment fittings and surrounding area cannot be satisfactorily cleaned to accomplish a borescope inspection, then accomplish the actions in paragraph (c) of this AD.
(3) Using a lighted borescope, inspect all four attachment fittings and the surrounding area for cracking.
(i) If a crack is found in the upper right attachment fitting, accomplish the actions in paragraph (c) of this AD.
(ii) If a crack is found in any of the other three attachment fittings, before further flight, accomplish the actions described in paragraph (f) of this AD.
(4) Visually inspect the upper longerons for cracking in accordance with the Accomplishment Instructions, paragraph 2.C., of SB600N-039. If a crack is found in the upper longeron, accomplish the actions in paragraph (e) of this AD.
Note 3: The reference in Figure 1 of SB600N-039 to the inspection hole at L167 mistakenly states that it was “Added by SB900-036.” Inspection holes at L167 and R167 were originally specified by SB600N-036.
(c) Within 25 hours TIS, unless accomplished previously:
(1) Thoroughly clean all attachment fittings and the surrounding areas, inspect the area for cracking, replace the upper right attachment fitting and all four nut plates, and paint the area inside of the attachment fittings in accordance with the Accomplishment Instructions, paragraph 2.B., of MD Helicopters Service Bulletin SB600N-043, dated April 13, 2006 (SB600N-043). If a crack is found in any of the other three attachment fittings, before further flight, accomplish the actions described in paragraph (f) of this AD.
(2) Using a 10x magnifying glass, inspect the attachment bolts' threads and shanks for wear or damage in accordance with paragraph 2.B., of SB600N-043. If wear or damage is present, replace the attachment bolts with airworthy bolts.
(d) Thereafter, at the specified intervals, remove the plug buttons from the inspection holes, and using a bright light, inspect the upper and lower left and upper and lower right attachment fittings, angles, and nut plates for a crack by following the Accomplishment Instruction paragraphs of SB600N-039, as follows, except you are not required to contact MDHI to meet the requirements of this AD.
(1) At intervals not to exceed 25 hours TIS, through inspection holes at L167 and R167, inspect the upper left and upper right attachment fittings, angles, and nut plates by following the Accomplishment Instructions, paragraphs 2.B.(2) through 2.B.(4), of SB600N-039.
(2) At intervals not to exceed 100 hours TIS, through inspection holes at L166 and R166, inspect the lower left and lower right attachment fittings, angles, and nut plates by following the Accomplishment Instructions, paragraphs 2.B.(2) through 2.B.(4), of SB600N-039.
(e) If a crack is found in the upper right attachment fitting, or in any angle, nut plate, longeron, or if thread wear or damage is found on any nut plate or bolt, before further flight, replace the cracked or worn or damaged part with an appropriate airworthy part, or accomplish the actions in paragraph (f) of this AD. If cracking is found in any of the other three attachment fittings, before further flight, accomplish the actions described in paragraph (f) of this AD.
(f) If required by paragraph (c)(1) of this AD, or if you choose to make this modification to comply with paragraph (e) of this AD, modify the aft fuselage to strengthen the tailboom attachments and the longerons by following the Accomplishment Instructions of MD Helicopters Technical Bulletin TB600N-007, Revision 1, dated April 13, 2006. Modifying the aft fuselage in accordance with this paragraph constitutes a terminating action for the requirements of this AD.
(g) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Contact the Manager, Los Angeles Aircraft Certification Office, Airframe Branch, FAA, ATTN: Jon Mowery, Aviation Safety Engineer, 3960 Paramount Blvd., Lakewood, California 90712, telephone (562) 627-5322, fax (562) 627-5210, for information about previously approved alternative methods of compliance.
(h) Special flight permits may be issued in accordance with 14 CFR 21.197 and 21.199 to operate the helicopter to the nearest maintenance facility capable of performing the inspections and modification.
(i) The inspections shall be done in accordance with MD Helicopters Service Bulletin SB600N-036, dated November 2, 2001. The incorporation by reference of that document was approved previously by the Director of the Federal Register, in accordance with 5 U.S.C. 552(a) and 1 CFR part 51, as of April 29, 2002 (67 FR 17934, April 12, 2002). The inspections, replacements and modifications shall be done in accordance with MD Helicopters Service Bulletin SB600N-039, dated December 9, 2003; MD Helicopters Service Bulletin SB600N-043, dated April 13, 2006; and MD Helicopters Technical Bulletin TB600N-007, Revision 1, dated April 13, 2006. The incorporation by reference of these documents was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from MD Helicopters Inc., Attn: Customer Support Division, 4555 E. McDowell Rd., Mail Stop M615, Mesa, Arizona 85215-9734, telephone 1-800-388-3378, fax 480-346-6813, or on the web at www.mdhelicopters.com. Copies may be inspected at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.
(j) This amendment becomes effective on April 27, 2006.
