AD 97-21-12

97-21-12 CONSTRUCCIONES AERONAUTICAS, S.A. CASA: Amendment 39-10165. Docket 96-NM-126-AD. Applicability: Model CN-235 series airplanes, as listed in CASA Service Bulletin SB-235-53-20, Revision 2, dated June 9, 1994 (for non-military airplanes); and Service Bulletin SB-235-53-20M, Revision 1, dated November 27, 1995 (for military airplanes); certificated in any category.

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (c) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed bythis AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent fatigue cracking in the area of the center wing-to-fuselage attachment fitting, which consequently could reduce the structural integrity of this area, accomplish the following:

(a) For non-military airplanes: Prior to the accumulation of 17,000 total landings, accomplish the actions specified in paragraphs (a)(1), (a)(2), and (a)(3) of this AD:

(1) Remove all parts and other items in the area of the center wing-to-fuselage attachment fitting, in accordance with Paragraph 2.B. ("Removal") of the Accomplishment Instructions of CASA Service Bulletin SB-235-53-20, Revision 2, dated June 9, 1994.

(2) After all parts and other items have been removed in accordance with paragraph (a)(1) of this AD, conduct a visual inspection, using a magnifier of at least 10x magnitude, to detect fatigue cracking in this area (ref: Figure 1, Sheet 1, of the service bulletin). If any cracking is detected, prior to further flight and prior to installing the reinforcing plate in accordance with paragraph (a)(3) of this AD, repair in a manner approved by the Manager, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate.

(3) Install a reinforcing plate having CASA part number (P/N) 35-25010-0101 in the attachment area of the center wing-to-fuselage attachment fitting, in accordance with the service bulletin.

(b) For military airplanes: Prior to the accumulation of 15,000 total landings, accomplish the actions specified in paragraphs (b)(1), (b)(2), and (b)(3) of this AD:

(1) Remove all parts and other items in the area of the center wing-to-fuselage attachment fitting, in accordance with Paragraph 2.B. ("Removal") of the Accomplishment Instructions of CASA Service Bulletin SB-235-53-20M, Revision 1, dated November 27, 1995.(2) After all parts and other items have been removed in accordance with paragraph (b)(1) of this AD, conduct a visual inspection, using a magnifier of at least 10x magnitude, to detect fatigue cracking in this area (ref: Figure 1, Sheet 1, of the service bulletin). If any cracking is detected, prior to further flight and prior to installing the reinforcing plate in accordance with paragraph (b)(3) of this AD, repair in a manner approved by the Manager, Standardization Branch, ANM-113, FAA.

(3) Install a reinforcing plate having CASA part number (P/N) 35-25010-0101 in the attachment area of the center wing-to-fuselage attachment fitting, in accordance with the service bulletin.

(c) 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. 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 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Standardization Branch, ANM-113.

(d) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

(e) Certain actions shall be done in accordance CASA Service Bulletin SB-235-53-20M, Revision 1, dated November 27, 1995 (for military airplanes); and CASA Service Bulletin SB-235-53-20, Revision 2, dated June 9, 1994 (for non-military airplanes), which contains the following list of effective pages:

Page Number Revision Level Shown on Page Date Shown on Page 1 1 April 13, 1994 2 2 June 9, 1994 3-11 Original July 29, 1993

This incorporation byreference 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 Construcciones Aeronauticas, S.A., Getafe, Madrid, Spain. 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.

NOTE 3: The subject of this AD is addressed in Spanish airworthiness directive 03/94, dated August 1994.

(f) This amendment becomes effective on November 24, 1997.