AD 93-03-14

93-03-14 BOEING: Amendment 39-8518. Docket 92-NM-235-AD. Supersedes AD 93-01-05, Amendment 39-8459.

Applicability: All Model 747 series airplanes, certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To prevent failure of the engine support structure and the inability of the strut to carry required engine operational loads, accomplish the following:

(a) For all Model 747 series airplanes, except JT9D-70-equipped airplanes: Inspect the forward bottle bore fuse pins in the rear diagonal brace of the inboard nacelle struts in accordance with paragraph (a)(1) or (a)(2) of this AD.

(1) Within 100 landings after August 5, 1981 (the effective date of AD 79- 22-03 R3, Amendment 39-4176), unless accomplished already within the last 250 landings, but not to exceed 1,200 landings from the previous inspection: Remove the retainer bolt and end caps from the fuse pins, part numbers 65B94182-3, 69B90410-1, -3, -4, -600, and 69B89612-3, and perform a visual inspection of the fuse pins to detect cracks in the machined shear section, in accordance with Boeing Service Bulletin 747-54-2066, dated November 7, 1979; Revision 1, dated October 10, 1980; or Revision 2, dated July 16, 1982. Repeat that inspection thereafter at intervals not to exceed 350 landings until the inspection required by paragraph (e) of this AD is accomplished.

(2) Within 100 landings after August 5, 1981 (the effective date of AD 79- 22-03 R3, Amendment 39-4176), unless accomplished already within the last 1,100 landings, but not to exceed 1,200 landings from the previous inspection: Remove the retainer bolt and end caps from the fuse pins, part numbers 65B94182-3, 69B90410-1, -3, -4, -600, and 69B89612-3, and perform an ultrasonic inspection of the fuse pins to detect cracks in the machined shear section, in accordance with Boeing Service Bulletin 747-54-2066, dated November 7, 1979; Revision 1, dated October 10, 1980; or Revision 2, dated July 16, 1982. Repeat that inspection thereafter at intervals not to exceed 1,200 landings until the inspection required by paragraph (e) of this AD is accomplished.

(b) After February 5, 1993 (the effective date of AD 93-01-05, Amendment 39- 8459), perform the repetitive inspections required by paragraph (a) of this AD only in accordance with the ultrasonic inspection method referenced in paragraph (a) of this AD.

(c) For Model 747 series airplanes listed in Boeing Service Bulletin 747-54-2101, dated April 11, 1983: Prior to the accumulation of 5,000 landings, or within 350 landings after January 9, 1984 (the effective date of AD 83-24-05, Amendment 39-4775), whichever occurs later, perform a visual or an ultrasonic inspection for cracks in the aft bottle bore fuse pin bore in recessed shear plane areas, in accordance with Boeing Service Bulletin 747-54-2101, dated April 11, 1983; or Revision 1, dated June 1, 1984. Repeat that inspection thereafter at intervals not to exceed 350 landings (if the previous inspection was visual) or 1,200 landings (if the previous inspection was ultrasonic) until the inspection required by paragraph (f) of this AD is accomplished.

(d) After February 5, 1993 (the effective date of AD 93-01-05, Amendment 39- 8459), perform the repetitive inspections required by paragraph (c) of this AD only in accordance with the ultrasonic inspection method referenced in paragraph (c).

(e) For diagonal brace forward bottle bore fuse pins: Perform an ultrasonic inspection to detect cracks and a detailed visual inspection to detect corrosion in the forward bottle bore fuse pins located in the diagonal braces on the inboard and outboard engine struts from each end of the pin, in accordance with Boeing Alert Service Bulletin 747-54A2153, dated December 23, 1992, at the time specified in paragraph (e)(1) of this AD. Accomplishment of this inspection terminates the repetitive inspection requirements of paragraph (a) of this AD. Thereafter, repeat these inspections at intervals not to exceed 1,000 landings.

(1) Inspect all engine positions at the later of the times specified in paragraphs (e)(1)(i) and (e)(1)(ii) of this AD:

(i) Prior to the accumulation of 3,000 landings after February 5, 1993 (the effective date of AD 93-01-05, Amendment 39-8459), or within 3 years since pin installation, whichever occurs first. Or

(ii) Within 90 days after February 5, 1993 (the effective date of AD 93-01-05, Amendment 39-8459).

NOTE: This AD does not require that these inspections be performed on forward 15-5 steel fuse pins or forward H-11 steel bolts in the diagonal brace.

(2) If any crack or corrosion is found as a result of the inspections required by paragraph (e) of this AD, prior to further flight, replace the cracked or corroded pin with a forward 15-5 steel fuse pin, in accordance with Boeing Alert Service Bulletin 747-54A2153, dated December 23, 1992. Installation of a forward 15-5 steel fuse pin constitutes terminating action for the repetitive inspections required by paragraph (e) of this AD.

(f) For diagonal brace aft bottle bore fuse pins and aft bulkhead fuse pins: Perform an ultrasonic inspection to detect cracks, and a detailed visual inspection to detect corrosion, in the aft bottle bore and aft bulkhead fuse pins in the diagonal brace on the inboard and outboard engine struts from each end of the pin, in accordance with Boeing Alert Service Bulletin 747- 54A2153, dated December 23, 1992, at the time specified in paragraph (f)(1) of this AD. Accomplishment of this inspection terminates the repetitive inspection requirements of paragraph (c) of this AD.

(1) Inspect all engine positions at the later of the times specified in paragraphs (f)(1)(i) and (f)(1)(ii) of this AD:

(i) Prior to the accumulation of 3,000 landings February 5, 1993 (the effective date of AD 93-01-05, Amendment 39-8459), or within 3 years since pin installation, whichever occurs first. Or

(ii) Within 90 days after February 5, 1993 (the effective date of AD 93-01-05, Amendment 39-8459).

(2) If any crack is found as a result of the inspections required by paragraph (f) of this AD, prior to further flight, replace the cracked pin with an aft bulkhead fuse pin, in accordance with Boeing Alert Service Bulletin 747-54A2153, dated December 23, 1992. Thereafter, accomplish the initial inspection required by paragraph (f) of this AD on the newly- installed aft bulkhead fuse pin.

(3) If any corrosion is found as a result of the inspections required by paragraph (f) of this AD, prior to further flight, accomplish paragraph (f)(3)(i) or (f)(3)(ii) of this AD, as applicable.

(i) If corrosion is found in any aft bottle bore fuse pin: Replace with an aft bulkhead fuse pin, in accordance with Boeing Alert Service Bulletin 747-54A2153, dated December 23, 1992.

(ii) If corrosion is found in any aft bulkhead fuse pin: Accomplish paragraph (f)(3)(ii)(A), (f)(3)(ii)(B), or (f)(3)(ii)(C) of this AD, as applicable.

(A) If the amount of corroded material that must be removed exceeds the limit specified in Figure 8 of the service bulletin, replace the corroded fuse pin with an aft bulkhead fuse pin, in accordance with the service bulletin. Thereafter, accomplish the initial inspection required by paragraph (f) of this AD on the newly-installed aft bulkhead fuse pin.

(B) If the amount of corroded material that must be removed is more than light, and equal to or less than the limit specified in Figure 8 of the service bulletin, rework the corroded fuse pin, or replace the corroded fuse pin with an aft bulkhead fuse pin, in accordance with the service bulletin. "Light" corrosion is characterized by discoloration or pitting to a depth of not more than 0.001-inch maximum. This type of corrosion can be removed normally by light hand sanding. A fuse pin that has been reworked in accordance with Figure 8 of the service bulletin must be replaced with an aft bulkhead fuse pin prior to the accumulation of 3,000 landings on the pin, or 3 years since the pin was reworked and reinstalled, whichever occurs first.

(C) If the corrosion is light, remove the corroded material from the fuse pin in accordance with the service bulletin. Thereafter, accomplish the repetitive inspections required by paragraph (f)(4) of this AD.

(4) Repeat the inspections required by paragraph (f) of this AD at the intervals specified in paragraph (f)(4)(i) or (f)(4)(ii) of this AD, as applicable:

(i) For aft bottle bore fuse pins: Repeat at intervals not to exceed 1,000 landings.

(ii) For aft bulkhead fuse pins: Repeat at intervals not to exceed 2,000 landings.

(g) 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, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO.

NOTE: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.

(h) Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate the airplane to a location where the requirements of this AD can be accomplished.

(i) The inspections, replacement, and repair shall be done in accordance with the following Boeing service bulletins, as applicable, which contain the specified effective pages:

Service Bulletin Referenced and Date

Page Number Revision Level Shown on Page Date Shown on Page 747-54-2066, November 7, 1979 1-7 Original November 7, 1979

747-54-2066, Revision 1, October 10, 1980 1-27 1 October 10, 1980

747-54-2066, Revision 2, July 16, 1982 1-17, 20, 27

18-19, 21-26 2

1 October 10, 1980

July 16, 1982

747-54-2101, April 11, 1983 1-27 Original April 11, 1983

747-54-2101 Revision 1, June 1, 1984 1-23 1 June 1, 1984

747-54A2153, December 23, 1992 1-56 Original December 23, 1992

This incorporation by reference was previously approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51, as of February 5, 1993 (58 FR 480, January 6, 1993). Copies may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

This AD, 93-03-14, Amendment 39-8518 supersedes AD 93-01-05, Amendment 39- 8459, which superseded AD 79-22-03 R3, Amendment 39-3598 as amended by Amendments 39- 3634 and 39-4001, 39-4176 and AD 83-24-05, Amendment 39-4775.

(j) This amendment becomes effective on March 18, 1993.