AD 93-14-07

93-14-07 AEROSPATIALE: Amendment 39-8631. Docket 93-NM-06-AD.

Applicability: Model ATR72-100 and -200 series airplanes; on which either Modification 03616, as described in Aerospatiale Service Bulletin ATR72-53-1027, dated December 18, 1992, or Modification 03584 have not been accomplished; certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To prevent loss of structural strength of the floor beam and pressure plate, or loss of cabin pressurization, accomplish the following:

(a) Prior to the accumulation of 1,000 total flight cycles, or within the next 30 days after the effective date of this AD, whichever occurs later, perform a detailed visual inspection to detect cracks of the floor beam at frame 26 of the fuselage in the buttock line 0 area, in accordance with Aerospatiale Service Bulletin ATR72-53-1026, Revision 1, dated January 22, 1993.

(1) If no crack is found, accomplish either paragraph (a)(1)(i) or (a)(1)(ii) of this AD:

(i) Thereafter, at intervals not to exceed 1,000 flight cycles, repeat the detailed visual inspection.

(ii) Within the next 1,000 flight cycles, install Modification 03616 in accordance with Aerospatiale Service Bulletin ATR72-53-1027, dated December 18, 1992. No further action is required by this AD.

(2) If a single crack is found that is less than 65 millimeters (mm) in length, accomplish either paragraph (a)(2)(i) or (a)(2)(ii) of this AD.

(i) Thereafter, at intervals not to exceed 750 flight cycles, repeat the detailed visual inspection.

(ii) Within the next 750 flight cycles after crack discovery, repair the crack in accordance with Aerospatiale Service Bulletin ATR72-53-1028, dated January 18, 1993. No further action is required by this AD.

(3) If a single crack is found that is equal to or greater than 65 mm but less than 80 mm in length: Within the next 250 flight cycles after crack discovery, repair the crack in accordance with Aerospatiale Service Bulletin ATR72-53-1028, dated January 18, 1993. No further action is required by this AD.

(4) If a single crack is found that is equal to or greater than 80 mm in length: Prior to further flight, repair the crack in accordance with Aerospatiale Service Bulletin ATR72-53-1028, dated January 18, 1993. No further action is required by this AD.

(5) If two or more cracks are found: Prior to further flight, repair the cracks in accordance with Aerospatiale Service Bulletin ATR72-53-1028, dated January 18, 1993. No further action is required by this AD.

(b) Prior to the accumulation of 1,000 total flight cycles, or within the next 30 days after the effective date of this AD, whichever occurs later, perform a high frequency eddy current (HFEC) inspection of the pressure plate forward and aft of the floor beam at frame 26 of the fuselage at buttock line 0, in accordance with Aerospatiale Service Bulletin ATR72-53-1026, Revision 1, dated January 22, 1993.

(1) If no crack is found, accomplish either paragraph (b)(1)(i) or (b)(1)(ii) of this AD:

(i) Thereafter, at intervals not to exceed 1,000 flight cycles, repeat the HFEC inspection.

(ii) Within the next 1,000 flight cycles, install Modification 03616 in accordance with Aerospatiale Service Bulletin ATR72-53-1027, dated December 18, 1992. No further action is required by this AD.

(2) If a single crack is found that is less than 65 millimeters (mm) in length, accomplish either paragraph (b)(2)(i) or (b)(2)(ii) of this AD:

(i) Thereafter, at intervals not to exceed 500 flight cycles, repeat the HFEC inspection.

(ii) Within the next 500 flight cycles after crack discovery, repair the crack in accordance with Aerospatiale Service Bulletin ATR72-53-1028, dated January 18, 1993. No further action is required by this AD.

(3) If a single crack is found that is equal to or greater than 65 mm but less than 80 mm in length: Withinthe next 250 flight cycles after crack discovery, repair the crack in accordance with Aerospatiale Service Bulletin ATR72-53-1028, dated January 18, 1993. No further action is required by this AD.

(4) If a single crack is found that is equal to or greater than 80 mm in length: Prior to further flight, repair the crack in accordance with Aerospatiale Service Bulletin ATR72-53-1028, dated January 18, 1993. No further action is required by this AD.

(5) If two or more cracks are found: Prior to further flight, repair the cracks in accordance with Aerospatiale Service Bulletin ATR72-53-1028, dated January 18, 1993. No further action is required by this AD.

(c) Within 6 months after the effective date of this AD, if no crack is present, install Modification 03616 in accordance with Aerospatiale Service Bulletin ATR72-53-1027, dated December 18, 1992; or, if any crack is present, repair in accordance with Aerospatiale Service Bulletin ATR72-53-1028, dated January 18, 1993.

(d) Installation of Modification 03616 in accordance with Aerospatiale Service Bulletin ATR72-53-1027, dated December 18, 1992; or repair in accordance with Aerospatiale Service Bulletin ATR72-53-1028, dated January 18, 1993; constitutes terminating action for the repetitive detailed visual inspections of the floor beam and repetitive HFEC inspections of the pressure plate required by this AD.

(e) 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, Standardization Branch, ANM-113, 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, Standardization Branch, ANM-113.

NOTE: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Standardization Branch, ANM-113.

(f) 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.

(g) The inspection shall be done in accordance with Aerospatiale Service Bulletin ATR72-53-1026, Revision 1, dated January 22, 1993. The installation shall be done in accordance with Aerospatiale Service Bulletin ATR72-53-1027, dated December 18, 1992. The repair shall be done in accordance with Aerospatiale Service Bulletin ATR72-53-1028, dated January 18, 1993. This incorporation by reference 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 Aerospatiale, 316 Route de Bayonne, 31060 Toulouse, Cedex 03, France. 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.

(h) This amendment becomes effective on September 10, 1993.