AD 2010-18-12

We are adopting a new airworthiness directive (AD) for all Robert E. Rust, Jr. Models DeHavilland DH.C1 Chipmunk 21, DH.C1 Chipmunk 22, and DH.C1 Chipmunk 22A airplanes. This AD requires you to do a one-time inspection of the flap operating system for an unapproved latch plate design installation, with replacement as necessary. This AD results from a report of a latch plate failing in service that was not made in accordance with the applicable de Havilland drawing. We are issuing this AD to detect and correct an unauthorized latch plate design installation which could result in an un-commanded retraction of the flaps. This failure could lead to a stall during a landing approach.

Final rule.

2010-18-12 Robert E. Rust, Jr.: Amendment 39-16426; Docket No. FAA- 2010-0632; Directorate Identifier 2010-CE-025-AD.

Effective Date

(a) This AD becomes effective on October 7, 2010.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Models DeHavilland DH.C1 Chipmunk 21, DH.C1 Chipmunk 22, and DH.C1 Chipmunk 22A airplanes, all serial numbers, that are certificated in any category.

Note: These airplanes are also identified as CHIPMUNK 22A, CHIPMUNK DHC-1T10, CHIPMUNK T.10 MK-22, DH.C1 MK22A, DHC-1, DHC-1 CHIPMUNK, DHC-1 CHIPMUNK 22, DHC-1 SERIES 22, or DHC-1 T.MK. 10.

Subject

(d) Air Transport Association of America (ATA) Code 27: Flight Controls.

Unsafe Condition

(e) This AD results from a report of a latch plate supplied under part number (P/N) C1-CF-1489 failing in service. The part in question was not manufactured to the applicable de Havilland drawing. The unapproved latch plate was made of a shaft that was pressed into a plate, rather than being machined from bar material as one piece. The shaft and plate on the unapproved part can become separated or bent, resulting in rapid wear and failure of the part. This condition, if not corrected, could result in an un-commanded retraction of the flaps. This failure could lead to a stall during a landing approach.

Compliance

(f) To address this problem, you must do the following, unless already done:

Actions
Compliance
Procedures
(1) Inspect the flap operating system to identify the P/N of the latch plate installed. If latch plate P/N C1-CF-1489 is installed, inspect the latch plate to determine if it is in compliance with the design standard. An unapproved latch plate P/N C1-CF-1489 is made from two pieces pressed together while one that complies with the design standard is machined in one piece from bar material.
Within 50 hours time-in-service (TIS) after October 7, 2010 (the effective date of this AD) or within 90 days after October7, 2010 (the effective date of this AD), whichever occurs first.
Follow de Havilland Support Limited Technical News Sheet (TNS) CT(C1) No 208 Issue 1, dated January 30, 2009.
(2) If during the inspection required in paragraph (f)(1) of this AD an unapproved latch plate P/N C1-CF-1489 is found, replace the latch plate with a latch plate that complies with the design standard. The following U.S. standard hardware may be substituted for the hardware specified in the service information:
(i) 1/16 diameter cotter pin that is P/N MS24665-153 (or equivalent) in place of split pin P/N SP90/C; and
(ii) Washer that is P/N MS15795-806B (or equivalent) in place of washer P/N SP13/B.
Before further flight after the inspection where the unapproved latch plate P/N C1-CF-1849 was found.
Follow de Havilland Support Limited TNS CT(C1) No 208 Issue 1, dated January 30, 2009.

Alternative Methods of Compliance (AMOCs)

(g) The Manager, Atlanta Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. Send information to ATTN: Carey O'Kelley, Aerospace Engineer, FAA, Atlanta ACO, 1701 Columbia Avenue, College Park, Georgia 30337; telephone: (404) 474- 5543; fax: (404) 474-5606. Before using any approved AMOC on any airplane to which the AMOC applies, notify your appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO.

Material Incorporated by Reference

(h) You must use de Havilland Support Limited TNS CT(C1) No 208 Issue 1, dated January 30, 2009, to do the actions required by this AD, unless the AD specifies otherwise.
(1) The Director of the Federal Register approved the incorporation by reference of this service information under 5 U.S.C. 552(a) and 1 CFR part 51.
(2) For service information identified in this AD, contact de Havilland Support Limited, Duxford Airfield, Cambridgeshire, CB22 4QR, England, phone: +44 (0) 1223 830090; fax: +44 (0) 1223 830085; e-mail: info@dhsupport.com; Internet: http://www.dhsupport.com/.
(3) You may review copies of the service information incorporated by reference for this AD at the FAA, Central Region, Office of the Regional Counsel, 901 Locust, Kansas City, Missouri 64106. For information on the availability of this material at the Central Region, call (816) 329-3768.
(4) You may also review copies of the service information incorporated by reference for this AD at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call (202) 741-6030, or go to: http:// www.archives.gov/federal_register/code_of_federal_regulations/ ibr_locations.html.

Discussion

On June 14, 2010, we issued a proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to all Robert E. Rust, Jr. Models DeHavilland DH.C1 Chipmunk 21, DH.C1 Chipmunk 22, and DH.C1 Chipmunk 22A airplanes. This proposal was published in the Federal Register as a notice of proposed rulemaking (NPRM) on June 21, 2010 (75 FR 34956). The NPRM proposed to require a one-time inspection of the flap operating system for an unapproved latch plate design installation with replacement as necessary.

Comments

We provided the public the opportunity to participate in developing this AD. We received no comments on the proposal or on the determination of the cost to the public.

Conclusion

We have carefully reviewed the available data and determined that air safety and the public interest require adopting the AD as proposed except for minor editorial corrections. We have determined that these minor corrections:
Are consistent with the intent that was proposed in the NPRM for correcting the unsafe condition; and
Do not add any additional burden upon the public than was already proposed in the NPRM.

Costs of Compliance

We estimate that this AD affects 64 airplanes in the U.S. registry.
We estimate the following costs to do the inspection:

Labor Cost
Parts Cost
Total Cost Per Airplane
Total Cost on U.S. Operators
3 work-hours X $85 per hour = $255
Not Applicable
$255
$16,320

We estimate the following costs to do any necessary replacements that would be required based on the results of the inspection. We have no way of determining the number of airplanes that may need this replacement:

Labor Cost
Parts Cost
Total Cost Per Airplane
.5 work-hour X $85 per hour = $42.50
$175
$217.50

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, Section 106 describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the agency's authority.
We are issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701, "General requirements.'' Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this AD.

Regulatory Findings

We have determined that this AD will not have federalism implications under Executive Order 13132. This AD will not have a substantial direct effect on the States, on the relationship between the national government and the States, or on the distribution of power andresponsibilities among the various levels of government.
For the reasons discussed above, I certify that this AD:
1. Is not a "significant regulatory action'' under Executive Order 12866;
2. Is not a "significant rule'' under the 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.
We prepared a summary of the costs to comply with this AD (and other information as included in the Regulatory Evaluation) and placed it in the AD Docket. You may get a copy of this summary by sending a request to us at the address listed under ADDRESSES. Include "Docket No. FAA-2010-0632; Directorate Identifier 2010-CE-025-AD'' in your request.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment

Accordingly, under 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.

Sec. 39.13 [Amended]

2. FAA amends Sec. 39.13 by adding the following new AD: