AD 99-07-13

This amendment adopts a new airworthiness directive (AD), applicable to certain CASA Model CN-235 series airplanes. This amendment requires a one-time visual inspection to detect relative movement or deformation of the joint areas of the rear attaching supports and lower skin of the left and right outer flaps; repetitive borescopic inspections to detect cracking of the spar and of the rear internal support fittings of the outer flaps; and corrective actions, if necessary. This amendment also provides for optional terminating action for the repetitive inspections. This amendment is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by this AD are intended to detect and correct fatigue cracking of the rear internal support fittings of the outer flap structure, which could result in failure of the outer flaps, and consequent reduced controllability of the airplane.

Final rule

99-07-13 CONSTRUCCIONES AERONAUTICAS, S.A. (CASA): Amendment 39-11098. Docket 98-NM-219-AD.
Applicability: Model CN-235 series airplanes, as listed in CASA Service Bulletin SB-235-57-20, dated December 23, 1997; and Model CN-235 series airplanes having serial number C-011; certificated in any category.

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been 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 detect and correct fatigue cracking of the rear internal support fittings of the outer flap structure, which could result in failure of the outer flaps, and consequent reduced controllability of the airplane, accomplish the following:

(a) Prior to the accumulation of 4,000 total landings, or within 30 days after the effective date of this AD, whichever occurs later, perform a one-time detailed visual inspection to detect relative movement or deformation of the joint areas of the rear attaching supports and lower skin of the left and right outer flaps, in accordance with CASA Maintenance Instructions COM 235-123, Revision 01, dated October 7, 1997.

(1) If no relative movement or deformation is detected: Within 300 landings, perform the requirements of paragraph (b) of this AD.

(2) If any relative movement or deformation is detected: Priorto further flight, perform the requirements of paragraph (b) of this AD.

(b) Remove the rear support attach bolts, one at a time, and perform a borescopic inspection to detect cracking of the spar and of the rear internal support fittings of the outer flaps, in accordance with CASA Maintenance Instructions COM 235-123, Revision 01, dated October 7, 1997.

(1) If no crack is detected, repeat the borescopic inspection thereafter at intervals not to exceed 600 landings until the replacement specified in paragraph (c) of this AD is accomplished.

(2) If any crack is detected, prior to further flight, replace the cracked outer flap with a new outer flap on which modified rear internal support fittings are installed, in accordance with CASA Service Bulletin SB-235-57-20, dated December 23, 1997. Such replacement constitutes terminating action for the repetitive borescopic inspection required by paragraph (b) of this AD for the replaced outer flap only.

(c) Accomplishment of the replacement specified in CASA Service Bulletin SB-235-57-20, dated December 23, 1997, constitutes terminating action for the repetitive borescopic inspections required by paragraph (b) of this AD.

(d) As of the effective date of this AD, no person shall install on any airplane an outer flap having part number 35-15501-00.

Alternative Methods of Compliance
(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, International Branch, ANM-116, 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, International Branch, ANM-116.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the International Branch, ANM-116. Special Flight Permits

(f) 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.

Incorporation by Reference
(g) The inspections shall be done in accordance with CASA Maintenance Instructions COM 235-123, Revision 01, dated October 7, 1997. The replacement, if accomplished, shall be done in accordance with CASA Service Bulletin SB-235-57-20, dated December 23, 1997, as applicable. 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 3:The subject of this AD is addressed in Spanish airworthiness directive 01/97, dated March 19, 1997.

(h) This amendment becomes effective on May 6, 1999.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain CASA Model CN-235 series airplanes was published in the Federal Register on January 20, 1999 (64 FR 3052). That action proposed to require a one-time visual inspection to detect relative movement or deformation of the joint areas of the rear attaching supports and lower skin of the left and right outer flaps; repetitive borescopic inspections to detect cracking of the spar and of the rear internal support fittings of the outer flaps; and corrective actions, if necessary. That action also proposed to provide for optional terminating action for the repetitive inspections.

Comments
Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were submitted in response to the proposal or the FAA's determination of the cost to the public.

Conclusion
The FAA has determined that air safety and the public interest require the adoption of the rule as proposed.

Cost Impact
The FAA estimates that 2 airplanes of U.S. registry will be affected by this AD, that it will take approximately 1 work hour per airplane to accomplish the required visual inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the visual inspection required by this AD on U.S. operators is estimated to be $120, or $60 per airplane.

It will take approximately 4 work hours to accomplish the required borescopic inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the borescopic inspection required by this AD on U.S. operators is estimated to be $480, or $240 per airplane, per inspection cycle.

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operatorwould accomplish those actions in the future if this AD were not adopted.

Should an operator elect to accomplish the terminating action that is provided by this AD action, it would take approximately 30 work hours to accomplish, at an average labor rate of $60 per work hour. The cost of required parts would be approximately $123,204 per airplane. Based on these figures, the cost impact of the optional terminating action would be $125,004 per airplane.

Regulatory Impact
The regulations adopted herein will not have substantial direct effects on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

For the reasons discussed above, I certify that this action (1) isnot a significant regulatory action under Executive Order 12866; (2) is not a significant rule under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39 - AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.

39.13 [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: