AD 98-16-23

This amendment adopts a new airworthiness directive (AD), applicable to all CASA Model CN-235 series airplanes, that requires repetitive high frequency eddy current (HFEC) inspections of the flap transmission shafts to detect cracking, and repetitive functional tests (checks) to verify proper operation of the flap braking sub-system; and corrective actions, if necessary. 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 cracking in the flap transmission shafts, and to correct a malfunctioning flap braking sub-system, which could result in the inability to move the flaps, or in an asymmetric flap condition, and consequent reduced controllability of the airplane.

Final rule

98-16-23 CONSTRUCCIONES AERONAUTICAS, S.A. (CASA): Amendment 39-10700. Docket 98-NM-160-AD.
Applicability: All CASA Model CN-235 series 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 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 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 cracking in the flap transmission shafts, and to correct a malfunctioning flap braking sub-system, which could result in the inability to move the flaps, or in an asymmetric flap condition, and consequent reduced controllability of the airplane; accomplish the following:

(a) Prior to the accumulation of 6,000 total landings, or within 30 days after the effective date of this AD, whichever occurs later, perform a high frequency eddy current (HFEC) inspection of the flap transmission shafts to detect cracking, in accordance with Annex I, dated June 16, 1997, of CASA Maintenance Instructions COM 235-113, Revision 02, dated June 16, 1997.

(1) If no cracking is detected, repeat the HFEC inspection thereafter at intervals not to exceed 2,000 landings.

(2) If any cracking is detected, prior to further flight, replace the cracked shaft with a new or serviceable shaft, in accordance with the maintenance instructions; and repeat the HFEC inspection thereafter at intervals not to exceed 2,000 landings.

(b) Prior to the accumulation of 6,000 total landings, or within 30 days after the effective date of this AD, whichever occurs later, perform a functional test (check) to verify proper operation of the flap braking sub-system, in accordance with Annex II, dated July 1, 1997, of CASA Maintenance Instructions COM 235-113, Revision 02, dated June 16, 1997.

(1) If no malfunction is detected, repeat the functional test thereafter at intervals not to exceed 300 landings.

(2) If any malfunction is detected, prior to further flight, replace any discrepant component with a new or serviceable component in accordance with the maintenance instructions; and repeat the functional test to verify proper operation of the flap braking sub-system; repeat the functional test thereafter at intervals not to exceed 300 landings.

(c) An alternative method of compliance or adjustment of the compliance time that provides an acceptable levelof safety may be used if approved by the Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate. Operators shall submit their request 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.

(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) The actions shall be done in accordance with CASA Maintenance Instructions COM 235-113, Revision 02, dated June 16, 1997, including Annex I, dated June 16, 1997, and Annex II, dated July 1, 1997. 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 11/96, Revision 1, dated June 19, 1997.

(f) This amendment becomes effective on September 11, 1998.

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 all CASA Model CN-235 series airplanes was published in the Federal Register on June 8, 1998 (63 FR 31142). That action proposed to require repetitive high frequency eddy current (HFEC) inspections of the flap transmission shafts to detect cracking, and repetitive functional tests (checks) to verify proper operation of the flap braking sub-system; and corrective actions, if necessary.

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 bythis AD, and that it will take approximately 30 work hours per airplane to accomplish the required inspection and functional test, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the inspection and functional test required by this AD on U.S. operators is estimated to be $3,600, or $1,800 per airplane, per cycle.

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

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) is not 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: