E9-20789. Airworthiness Directives; Twin Commander Aircraft Corporation Models 690, 690A, and 690B Airplanes

AGENCY:

Federal Aviation Administration (FAA), Department of Transportation (DOT).

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

We propose to adopt a new airworthiness directive (AD) for certain Twin Commander Aircraft Corporation Models 690, 690A, and 690B airplanes. This proposed AD would require you to inspect between the surface of the left-hand (LH) and right-hand (RH) upper wing skins and the engine mount beam support straps for any signs of corrosion, replace the upper steel straps with parts of improved design, and modify both wings. This proposed AD results from reports that corrosion was found between the mating surfaces of the wing upper skin surface and the engine mount beam support straps. We are proposing this AD to detect and correct corrosion on the engine mount beam support straps and the upper wing skins, which could result in failure of the engine mount beam support straps. This failure could lead to loss of the engine and possible loss of control of the airplane.

DATES:

We must receive comments on this proposed AD by October 13, 2009.

ADDRESSES:

Use one of the following addresses to comment on this proposed AD:

• Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
• Fax: [phone].
• Mail: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590.
• Hand Delivery: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this proposed AD, contact Twin Commander Aircraft, LLC, 19010 59th Drive, NE., Arlington, WA 98223, telephone: [phone]; fax: [phone]; Internet: www.twincommander.com.

FOR FURTHER INFORMATION CONTACT:

Vince Massey, Aerospace Engineer, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone: [phone]; fax: [phone]; e-mail: [e-mail].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or arguments regarding this proposed AD. Send your comments to an address listed under the ADDRESSES section. Include the docket number, “FAA-2009-0778; Directorate Identifier 2009-CE-040-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments received by the closing date and may amend the proposed AD in light of those comments.

We will post all comments we receive, without change, to http://www.regulations.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact we receive concerning this proposed AD.

Discussion

We have received a report that corrosion was found between the mating surfaces of the wing upper skin surface and the engine mount beam support straps. These straps carry engine loads from the support beams into the upper wing skins and wing internal support structure. Severe corrosion of the straps can lead to inability to carry engine loads.

This condition, if not corrected, could result in failure of the engine mount beam support straps. This failure could lead to loss of the engine and possible loss of control of the airplane.

Relevant Service Information

We have reviewed Twin Commander Aircraft LLC Alert Service Bulletin No. 237, dated May 13, 2005. The service information describes procedures for inspecting the surface of the LH and RH upper wing skins and the engine mount beam support straps for any signs of corrosion, replacing the upper steel straps with parts of improved design, and modifying both wings.

We have reviewed Twin Commander Aircraft Corporation Custom Kit No. 150, dated July 8, 1994. The service information describes procedures for installing inspection access holes in the LH and RH upper wing skins.

We have reviewed Gulfstream American Corporation Service Bulletin No. 182, dated March 2, 1981. The service information describes procedures for installing additional wing fasteners on the LH and RH wing.

FAA's Determination and Requirements of the Proposed AD

We are proposing this AD because we evaluated all information and determined the unsafe condition described previously is likely to exist or develop on other products of the same type design. This proposed AD would require you to inspect between the surface of the LH and RH upper wing skins and the engine mount beam support straps for any signs of corrosion, replace the upper steel straps with parts of improved design, and modify both wings.

Costs of Compliance

We estimate that this proposed AD would affect 275 airplanes in the U.S. registry.

We estimate the following costs to do the proposed inspection:

Labor cost	Parts cost	Total cost per airplane	Total cost on U.S. operators
80 work-hours × $80 per hour = $6,400	Not applicable	$6,400	$1,760,000

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

Short Modification—Option A*

Labor cost	Parts cost	Total cost per airplane per side
250 work-hours × $80 per hour = $20,000 per side	$9,170 per kit per side	$29,170

Middle Modification—Option B*

Labor cost	Parts cost	Total cost per airplane per side
280 work-hours × $80 per hour = $22,400 per side	$9,170 per kit per side	$31,570

Long Modification—Option C*

Labor cost	Parts cost	Total cost per airplane per side
320 work-hours × $80 per hour = $25,600 per side	$9,170 per kit per side	$34,770

Note:

*Depending on airplane configuration, airplanes with rectangular plates would need the Plate and Hardware Kit (SB237-4) at $2,090 per side. Labor to install this kit is included in Options A, B, and C.

Strap Only Replacement—Option D

Labor cost	Parts cost	Total cost per airplane per side
75 work-hours × $80 per hour = $6,000 per side	$6,190 per strap per side	$12,190

We estimate the following costs to do the proposed installation of access holes:

Labor cost	Parts cost	Total cost per airplane	Total cost on U.S. operators
30 work-hours × $80 per hour = $2,400	$1,293	$3,693	$1,015,575

We estimate the following costs to do the proposed wing fastener modification:

Labor cost	Parts cost	Total cost per airplane	Total cost on U.S. operators
8.5 work-hours × $80 per hour = $680	$250	$930	$255,750

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 rulemaking action.

Regulatory Findings

We have determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would 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 and responsibilities among the various levels of government.

For the reasons discussed above, I certify that the proposed regulation:

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 regulatory evaluation of the estimated costs to comply with this proposed AD and placed it in the AD docket.

Examining the AD Docket

You may examine the AD docket that contains the proposed AD, the regulatory evaluation, any comments received, and other information on the Internet at http://www.regulations.gov;​; or in person at the Docket Management Facility between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Office (telephone [phone]) is located at the street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Incorporation by reference
• Safety

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 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. The FAA amends § 39.13 by adding the following new AD:

Twin Commander Aircraft Corporation: Docket No. FAA-2009-0778; Directorate Identifier 2009-CE-040-AD.

Comments Due Date

(a) We must receive comments on this airworthiness directive (AD) action by October 13, 2009.

Affected ADs

(b) None.

Applicability

(c) This AD applies to the following airplane models and serial numbers that are certificated in any category:

Models	Serial Nos. (S/Ns)
690	All S/Ns.
690A	All S/N except 11195 and 11279.
690B	All S/Ns except 11361, 11383, 11527, and 11536.

Unsafe Condition

(d) This AD results from reports that corrosion was found between the mating surfaces of the wing upper skin surface and the engine mount beam support straps. We are issuing this AD to detect and correct corrosion on the engine mount beam support straps and upper wing skins, which could result in failure of the engine mount beam support straps. This failure could lead to loss of the engine and possible loss of control of the airplane.

Compliance

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

Actions	Compliance	Procedures
(1) Inspect between the surface of the left-hand (LH) and right-hand (RH) upper wing skins and the engine mount beam support straps for any signs of corrosion and determine the extent of any corrosion found	Within the next 150 hours time-in-service after the effective date of this AD or within the next 12 months after the effective date of this AD, whichever occurs first	Follow Twin Commander Aircraft LLC Alert Service Bulletin No. 237, dated May 13, 2005, pages 1 through 14.
(2) Install modification access holes in the LH and RH lower wing skins	Before further flight after the inspection required in paragraph (e)(1) of this AD	Follow the Accomplishment Instructions, steps 1 through 4 and 6 through 9, of Twin Commander Aircraft Corporation Custom Kit No. 150, dated July 8, 1994, as specified in Twin Commander Aircraft LLC Alert Service Bulletin No. 237, dated May 13, 2005.
(3) If corrosion damage is found during the inspection required in paragraph (e)(1) of this AD, perform necessary modification	Before further flight after the inspection required in paragraph (e)(1) of this AD	Follow Twin Commander Aircraft LLC Alert Service Bulletin No. 237, dated May 13, 2005, Part II, Options A, B, or C, on pages 15 through 29, and 31.
(4) If corrosion damage is not found during the inspection required in paragraph (e)(1) of this AD, do the upper steel strap replacements	Before further flight after the inspection required in paragraph (e)(1) of this AD	Follow Twin Commander Aircraft LLC Alert Service Bulletin No. 237, dated May 13, 2005, Part II, Option D, on pages 30 and 31.
(5) Install additional wing fasteners on the LH and RH wing	Before further flight after the inspection required in paragraph (e)(1) of the AD	Follow Gulfstream American Corporation Service Bulletin No. 182, dated March 2, 1981.

Note:

Although not required by this AD, we highly recommend compliance with Twin Commander Aircraft Corporation Service Bulletin No. 217, Revision No. 1, dated May 26, 1993, Engine Nacelle Firewall Reinforcement; and Twin Commander Aircraft LLC Alert Service Bulletin No. 239, dated February 13, 2006, Outboard Flap—Inboard Hinge Inspection & Reinforcement.

Alternative Methods of Compliance (AMOCs)

(f) The Manager, Seattle 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: Vince Massey, Aerospace Engineer, FAA, Seattle ACO, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone: (425) 917-6475; fax: [phone]; e-mail: [e-mail]. 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.

Related Information

(g) To get copies of the service information referenced in this AD, contact Twin Commander Aircraft, LLC, 19010 59th Drive, NE., Arlington, WA 98223, telephone: [phone]; fax: [phone]; Internet: www.twincommander.com. To view the AD docket, go to U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590, or on the Internet at http://www.regulations.gov.

Issued in Kansas City, Missouri, on August 21, 2009.

Kim Smith,

Manager, Small Airplane Directorate, Aircraft Certification Service.