AD 97-21-06 ACTIVE

97-21-06 CASA: Amendment 39-10159. Docket 96-NM-137-AD.
Applicability: CASA Model CN-235 airplanes; as listed in CASA Service Bulletin SB-235-27-05, Revision 1, dated September 29, 1993 (non-military airplanes), and CASA Service Bulletin SB-235-27-05M, Revision 2, dated January 25, 1996 (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 (e) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this 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 loss of control of the elevator and/or rudder, due to failure of the elevator and/or rudder assemblies as a result of stress corrosion cracking in the torsion tubes and fittings, accomplish the following:

NOTE 2: Actions required by this AD that were accomplished previous to the effective date of this AD, and in accordance with earlier versions of the specified CASA service bulletins, are considered acceptable for compliance with the applicable requirements of this AD.

(a) At the applicable time specified in either paragraph (a)(1) or (a)(2) of this AD, conduct a visual inspection of the torsion (torsion) tubes on the elevator and rudder assemblies to detect stress corrosion cracking, in accordance with CASA Service Bulletin SB-235-27-05, Revision 1, dated September 29, 1993 (for non-military airplanes) or CASA Service Bulletin SB-235-27-05M, Revision 2, dated January 25, 1996 (for military airplanes), as applicable.

(1) For airplanes that have accumulated more than 600 total hours time-in-service, or more than 1,000 total landings, as of the effective date of this AD: Conduct the inspection required by paragraph (a) of this AD prior to the accumulation of 50 hours time-in-service, or 100 landings, or within 3 months, after the effective date of this AD, whichever occurs first.

(2) For all other airplanes: Conduct the inspection required by paragraph (a) of this AD prior to the accumulation of 600 total hours time-in-service, or 1,000 total landings, or within 6 months, after the effective date of this AD, whichever occurs first.

(b) If no cracking is detected during the inspection required by paragraph (a) of this AD, repeat that inspection at intervals not to exceed 600 hours time-in-service, or 1,000 landings, or 6 months, whichever occurs first.(c) If any cracking is detected during the inspection required by paragraph (a) of this AD, prior to further flight, accomplish either paragraph (c)(1) or (c)(2) of this AD.

(1) Replace cracked parts with new parts of the original design, in accordance with the service bulletin. After replacement, repeat the visual inspection required by paragraph (a) of this AD at intervals not to exceed 600 hours time-in-service, or 1,000 landings, or 6 months, whichever occurs first. OR

(2) Replace cracked parts with newly-designed parts, in accordance with CASA Service Bulletin SB-235-27-05, Revision 1, dated September 29, 1993 (for non-military airplanes); or CASA Service Bulletin SB-235-27-05M, Revision 2, dated January 25, 1996 (for military airplanes); as applicable. This replacement constitutes terminating action for the repetitive visual inspections of that part required by paragraph (b) of this AD.

(d) Within 2 years after the effective date of this AD, replace all original design parts comprising the torsion tube assemblies on the elevator and rudder assemblies with newly-designed parts, in accordance with CASA Service Bulletin SB-235-27-05, Revision 1, dated September 29, 1993 (for non-military airplanes); or CASA Service Bulletin SB-235-27-05M, Revision 2, dated January 25, 1996 (for military airplanes); as applicable. This action constitutes terminating action for the inspection requirements of 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 3: 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 sections 21.197 and P21.199 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.

(g) The actions shall be done in accordance with CASA Service Bulletin SB-235-27-05, Revision 1, dated September 29, 1993; and CASA Service Bulletin SB-235-27-05M, Revision 2, dated January 25, 1996; as applicable; which contain the specified effective pages:

Service Bulletin
Referenced and Date

Page Number
Revision Level
Shown on Page
Date
Shown on Page
SB-235-27-05,
Revision 1,
September 29, 1993
1, 2

3-23
1

Original
September 29, 1993

February 5, 1993
SB-235-27-05M,
Revision 2,
January 25, 1996
1

2-23
2

Original
January 25, 1996

October 28, 1991

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 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 4: The subject of this AD is addressed in Spanish airworthiness directive 06/94, dated August 1994.

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