AD 99-22-06

This amendment supersedes an existing airworthiness directive (AD), applicable to all CASA Model CN-235 series airplanes, that currently requires repetitive eddy current inspections to detect fatigue cracks in the nose landing gear (NLG) turning tube, and replacement of cracked tubes. This amendment adds a requirement for the replacement of the existing NLG turning tube constructed of aluminum alloy with a new NLG turning tube made of steel; such replacement terminates 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 prevent fatigue cracking and failure of the NLG turning tube, which could result in reduced structural integrity of the NLG.

Final rule

99-22-06 CONSTRUCCIONES AERONAUTICAS, S.A. (CASA): Amendment 39-11384. Docket 99-NM-117-AD. Supersedes AD 97-02-17, Amendment 39-9902.
Applicability: All Model CN-235 series airplanes; including Model CN-235 series airplane, 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 (f) 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 fatigue cracking and failure of the nose landing gear (NLG) turning tube, which could result in reduced structural integrity of the NLG, accomplish the following:
RESTATEMENT OF REQUIREMENTS OF AD 97-02-17, AMENDMENT 39-9902:

(a) At the applicable time specified in either paragraph (a)(1) or (a)(2) of this AD, conduct a high frequency eddy current (HFEC) inspection to detect fatigue cracking in the NLG turning tube, in accordance with the procedures specified in Annex 1 and Annex 2 of CASA Maintenance Instructions COM 235-092, Revision 02, dated May 5, 1995.

(1) For Model CN-235 airplanes [Basic model; Maximum Takeoff Weight (MTOW) = 31,746 lbs. (14,400 kgs.)]: Conduct the inspection prior to or upon the accumulation of 6,000 landings on the NLG turning tube, or within 50 landings after March 4, 1997 (the effective date of AD 97-02-17, amendment 39-9902), whichever occurs later.

(2) For Model CN-235-100 series airplanes [MTOW = 33,290 lbs. (15,100 kgs.)] and Model CN-235-200 series airplanes [MTOW = 34,833 lbs. (15,800 kgs)]: Conduct the inspection prior to or upon the accumulation of 4,800 landings on the NLG turning tube, or within 50 landings after March 4, 1997, whichever occurs later.

(b) If no cracking is detected during the inspection required by paragraph (a) of this AD, repeat the inspection thereafter at intervals not to exceed 200 landings until the requirements of paragraph (d) are accomplished.

(c) If any cracking is detected during any inspection required by paragraph (a) or (b) of this AD, prior to further flight, accomplish the actions required by paragraph (c)(1) or (c)(2) of this AD. After the effective date of this AD, only the actions specified by paragraph (c)(2) of this AD shall be accomplished.

(1) Replace the NLG turning tube with a new unit in accordance with CASA Maintenance Instructions COM235-092, Revision 02, dated May 5, 1995. After replacement, repeat the HFEC inspection prior to or upon the accumulation of 6,000 landings on the new NLG turning tube installed on Model CN-325 airplanes (basic model); or prior to or upon the accumulation of 4,800 landings on the new NLG turning tube installed on Model CN-325-100 and -200 series airplanes. Thereafter, repeat the inspection at intervals not to exceed 200 landings.

(2) Remove the NLG turning tube, P/N GA 63433, from the NLG yoke assembly and install a new turning tube, P/N GA 65924, and identify the modified NLG with a P/N SB-A0002-0101 data plate with the service bulletin number inscribed, in accordance with CASA Service Bulletin 35-CSB-32-001, dated February 16, 1999.

NEW REQUIREMENTS OF THIS AD:
(d) Remove the NLG turning tube, P/N GA 63433, from the NLG yoke assembly and install a new turning tube, P/N GA 65924, and identify the modified NLG with a P/N SB-A0002-0101 data plate with the service bulletinnumber inscribed, in accordance with CASA Service Bulletin 35-CSB-32-001, dated February 16, 1999. Except as provided by paragraph (c)(2) of this AD, accomplish the actions at the later of the times specified in paragraphs (d)(1) and (d)(2) of this AD. Accomplishment of these actions constitutes terminating action for the requirements of this AD.

(1) Prior to the accumulation of 4,800 total flight cycles; or

(2) Within 1 year or 200 landings after the effective date of this AD, whichever occurs first.

(e) As of the effective date of this AD, no person shall install a NLG turning tube, P/N GA 63433, on any airplane.

Alternative Methods of Compliance
(f) 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 MaintenanceInspector, 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
(g) 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
(h) The actions shall be done in accordance with CASA Maintenance Instructions COM 235-092, Revision 02, dated May 5, 1995; or CASA Service Bulletin 35-CSB-32-001, dated February 16, 1999; as applicable.

(1) The incorporation by reference of CASA Service Bulletin 35-CSB-32-001, dated February 16, 1999, is approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51.(2) The incorporation of reference of CASA Maintenance Instructions COM 235-092, Revision 02, dated May 5, 1995, was approved previously by the Director of the Federal Register as of March 4, 1997 (62 FR 3994, January 28, 1997).

(3) 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 01/95, Rev. 2, dated February 15, 1999.

(i) This amendment becomes effective on November 26, 1999.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 97-02-17, amendment 39-9902 (62 FR 3994, January 28, 1997), which is applicable to all CASA Model CN-235 series airplanes, was published in the Federal Register on August 12, 1999 (64 FR 43953). The action proposed to supersede AD 97-02-17, to continue to require repetitive eddy current inspections to detect fatigue cracks in the nose landing gear (NLG) turning tube, and replacement of cracked tubes. The action proposed to add a requirement to replace the existing NLG turning tube constructed of aluminum alloy with a new NLG turning tube made of steel, which would terminate 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.

The actions that are currently required by AD 97-02-17, and retained in this AD, take approximately 8 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the currently required actions on U.S. operators is estimated to be $480 per airplane.

The new actions that are required by this AD action will take approximately 16 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts will cost approximately $20,722 per airplane. Based on these figures, the cost impact of the actions required by this AD on U.S. operators is estimated to be $43,364, or $21,682 per airplane.

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any ofthe 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 removing amendment 39-9902 (62 FR 3994, January 28, 1997), and by adding a new airworthiness directive (AD), amendment 39-11384, to read as follows: