AD 79-23-03 R1

79-23-03 R1 MCDONNELL DOUGLAS HELICOPTER COMPANY (HUGHES HELICOPTERS, INC.): Amendment 39-3608 as amended by Amendment 39-5282. Applies to Models 269A, 269A-1, 269B, and 269C, including military TH-55A, certificated in any category, equipped with tail rotor blades designated below:

GROUP I GROUP II P/N 269A6124 P/N 269A6035-21, S/N's 0877 and prior 269A6124-9 P/N 269A6035-23, S/N'S 2710 and Prior 269A6035

269A6035-9

269A6035-17

269A6035-19

269A6035-M

269ASK15

269-6100

Compliance required as indicated.

To detect possible corrosion, cracks, pitting, and other defects, inspect by visual or other specified means the affected tail rotor blades and replace or rework in accordance with the instructions specified in the applicable Hughes Service Information Notice (SIN) specified below:

SIN No. N-130, dated August 28, 1975, applies to Group I tail rotor blades.

SIN No. N-162, dated October 12, 1979, applies to Group II tail rotor blades.

(a) Inspect tail rotor blades with 500 or more hours time in service on the effective date of this AD within the next 100 hours additional time in service, or within six (6) calendar months from the effective date of this AD, whichever occurs earlier.

(1) For Group I blades, perform the visual and X-ray inspections, corrosion removal, casting procedure, metal treatment procedure, corrosion protection procedure, and fiberglass inspection - repair/spar exterior inspection procedure set forth in Parts I through VIII of the applicable Hughes SIN referenced above.

(2) For Group II blades, perform the visual inspection and/or corrosion protection procedure for the tail rotor blade spar interior set forth in Parts I and III of the applicable Hughes SIN referenced above.

(b) Inspect tail rotor blades with less than 500 hours time in service on the effective date of this AD prior to accumulating a total time in service of 600 hours, or within six (6) calendar months from the effective date of this AD, whichever occurs earlier.

(1) For Group I blades, perform (a)(1) of this AD.

(2) For Group II blades, perform (a)(2) of this AD.

(c) For blades, P/N 269A6035-17 and 269A6035-19, with serial numbers listed at Part XI - Table 1, of the Hughes SIN referenced above, perform the Rockwell hardness test in accordance with Part XI of the Hughes SIN within the next 100 hours time in service after the effective date of this AD, unless already accomplished.

(d) Perform the inspections and procedures described in paragraphs (a)(1) and (a)(2) on Group I and Group II tail rotor blades, respectively, prior to the installation of spare blades or rotors on the aircraft.

(e) Perform the Rockwell hardness test specified in Part XI of Hughes SIN No. N-130, dated August 28, 1975, on spare blades or rotors with blades P/N 269A6035-17 and 269A6035-19, with serial numbers listed at Part XI - Table 1, of the referenced SIN, prior to the installation of these blades or rotors on the aircraft.

(f) Inspect tail rotor blades at intervals not to exceed twelve (12) months from the last inspection required by this AD, or twelve months from the effective date of this AD for blades identified in paragraphs (g)(1) and (g)(2) as specified:

(1) For Group I blades, conduct visual and X-ray inspections specified in Part X of SIN No. N-130 referenced above.

(2) For Group II blades, visually inspect per Part I of SIN No. N-162 referenced above.

(g) The repetitive inspections of paragraph (f) are applicable to the following blades, however, paragraphs (a), (b), and (d) of this AD need not be accomplished on:

(1) Group I blades marked with a green dot as identified in the preface of Hughes SIN No. N-130 referenced above.

(2) Group II blades marked with a 1/4 inch diameter white paint dot above the data plate on the rotor blade spar.

(h) Repair or rework eligible blades, as specified in the applicable Hughes SIN referenced above, prior to further flight. Blades that exceed limits specified in the Hughes SIN and are, therefore, not repairable must be marked in a conspicuous manner or destroyed, so as to prevent inadvertent return to service.

(i) Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base for the accomplishment of inspections required by this AD.

(j) Alternative inspections, modifications or other actions which provide an equivalent level of safety may be used when approved by the Manager, Western Aircraft Certification Office, ANM-170W, FAA, Northwest Mountain Region, P.O. Box 92007, Worldway Postal Center, Los Angeles, California 90009-2007.

Amendment 39-3608 superseded Amendment 39-2368 (42 FR 740), AD 75-20-01.

Amendment 39-3608 became effective November 19, 1979.

This Amendment 39-5282 becomes effective May 19, 1986.