E6-912. Airworthiness Directives; Mitsubishi Heavy Industries MU-2B Series Airplanes

AGENCY:

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

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for all Mitsubishi Heavy Industries (MHI) MU-2B series airplanes. This proposed AD would require you to do the following: Remove and visually inspect the wing attach barrel nuts, bolts, and retainers for cracks, corrosion, and fractures; replace any cracked, corroded, or fractured parts; inspect reusable barrel nuts and bolts for deformation and irregularities in the threads; replace any deformed or irregular parts; and install new or reusable parts and torque to the correct value. This proposed AD results from a recent safety evaluation that used a data-driven approach to evaluate the design, operation, and maintenance of the MU-2B series airplanes in order to determine their safety and define what steps, if any, are necessary to ensure their safe operation. Part of that evaluation was the identification of unsafe conditions that exist or could develop on the affected type design airplanes. We are issuing this proposed AD to detect and correct cracks, corrosion, fractures, and incorrect torque values in the wing attach barrel nuts, which could result in failure of the wing barrel nuts and/or associated wing attachment hardware. This failure could lead to in-flight separation of the outer wing from the center wing section and result in loss of controlled flight.

DATES:

We must receive comments on this proposed AD by February 27, 2006.

ADDRESSES:

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

• DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
• Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
• Mail: Docket Management Facility; U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, Washington, DC 20590.
• Fax: [phone].
• Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

Contact Mitsubishi Heavy Industries, Ltd., Nagoya Aerospace Systems Works, 10, OYE-CHO, Minato-Ku, Nagoya, Japan, or Turbine Aircraft Services, Inc., 4550 Jimmy Doolittle Drive, Addison, Texas 75001; telephone: [phone]; facsimile: [phone], for the service information identified in this proposed AD.

You may examine the comments on this proposed AD in the AD docket on the Internet at http://dms.dot.gov.

FOR FURTHER INFORMATION CONTACT:

Andrew McAnaul, Aerospace Engineer, ASW-150 (c/o MIDO-43), 10100 Reunion Place, Suite 650, San Antonio, Texas 78216; telephone: [phone]; facsimile: [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

How do I comment on this proposed AD? We invite you to send any written relevant data, views, or arguments regarding this proposal. Send your comments to an address listed under ADDRESSES. Include the docket number, “FAA-2006-23578; Directorate Identifier 2006-CE-01-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://dms.dot.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this proposed rulemaking. Using the search function of the DOT docket web site, anyone can find and read the comments received into any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78) or you may visit http://dms.dot.gov.

Examining the Dockets

Where can I go to view the docket information? You may examine the docket that contains the proposal, any comments received and any final disposition on the Internet at http://dms.dot.gov, or in person at the DOT Docket Offices between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Office (telephone [phone]) is located on the plaza level of the Department of Transportation NASSIF Building at the street address stated in ADDRESSES. Comments will be available in the AD docket shortly after the Docket Management Facility receives them.

Discussion

What events have caused this proposed AD? Recent accidents and the service history of the Mitsubishi MU-2B series airplanes prompted FAA to conduct an MU-2B Safety Evaluation. This evaluation used a data-driven approach to evaluate the design, operation, and maintenance of MU-2B series airplanes in order to determine their safety and define what steps, if any, are necessary to ensure their safe operation.

The safety evaluation provided an in-depth review and analysis of MU-2B incidents, accidents, safety data, pilot training requirements, engine reliability, and commercial operations. In conducting this evaluation, the team employed new analysis tools that provided a much more detailed root cause analysis of the MU-2B problems than was previously possible.

Part of that evaluation was to identify unsafe conditions that exist or could develop on the affected type design airplanes. One of these conditions is the discovery of the right wing upper forward and lower forward barrel nuts found cracked during a scheduled 7,500-hour inspection on one of the affected airplanes. The manufacturer conducted additional investigations of the barrel nuts on other affected airplanes. The result of this investigation revealed no other cracked barrel nuts. However, it was discovered that several airplanes had over-torqued barrel nuts, which could result in cracking.

What is the potential impact if FAA took no action? This condition, if not detected and corrected, could result in failure of the wing barrel nuts and/or associated wing attachment hardware. This failure could lead to in-flight separation of the outer wing from the center wing section and result in loss of controlled flight.

Relevant Service Information

Is there service information that applies to this subject? We have reviewed Mitsubishi Heavy Industries, Ltd. MU-2 Service Bulletin referenced as JCAB T.C.: No. 241, dated July 14, 2004, and MU-2 Service Bulletin referenced as FAA T.C.: No. 103/57-004, dated August 2, 2004.

What are the provisions of this service information? These service bulletins describe procedures for:

• Removing and inspecting the wing attach barrel nuts and retainer for cracks, corrosion, and fractures;
• Replacing any wing attach barrel nuts and retainer with cracks, corrosion, or fractures;
• Inspecting any bolts or barrel nuts to be reused for deformation or irregularities in the threads;
• Replacing any bolts or barrel nuts with deformation or irregularities in the threads; and
• Reinstalling the wing attach barrel nuts and hardware to the correct torque value.

Since Japan is the State of Design for the affected airplanes on one of the two type certificates, did the Japan Civil Airworthiness Board (JCAB) take any action? The MU-2B series airplane was initially certificated in 1965 and again in 1976 under two separate type certificates that consist of basically the same type design. Japan is the State of Design for TC No. A2PC, and the United States is the State of Design for TC No. A10SW. The affected models are as follows (where models are duplicated, specific serial numbers are specified in the individual TCs):

Type certificate	Affected models
A10SW	MU-2B-25, MU-2B-26, MU-2B-26A, MU-2B-35, MU-2B-36, MU-2B-36A, MU-2B-40, and MU-2B-60.
A2PC	MU-2B, MU-2B-10, MU-2B-15, MU-2B-20, MU-2B-25, MU-2B-26, MU-2B-30, MU-2B-35, and MU-2B-36.

The JCAB approved Mitsubishi Heavy Industries, Ltd. MU-2 Service Bulletin referenced as JCAB T.C.: No. 241, dated July 14, 2004, and MU-2 Service Bulletin referenced FAA T.C.: No. 103/57-004, dated August 2, 2004, to ensure the continued airworthiness of these airplanes in Japan.

FAA's Determination and Requirements of the Proposed AD

Why have we determined AD action is necessary and what would this proposed AD require? We are proposing this AD to address an unsafe condition that we determined is likely to exist or develop on other products of this same type design. This proposed AD would require you to do the following:

• Remove and visually inspect the wing attach barrel nuts, bolts, and retainers for cracks, corrosion, and fractures;
• Replace any cracked, corroded, or fractured wing attach barrel nuts, bolts, and retainers with new parts;
• Inspect reusable barrel nuts and bolts for deformation and irregularities in the threads; replace any deformed or irregular wing attach barrel nuts or bolts with new parts; and
• Install new or reusable parts and torque to the correct value.

This proposed AD would require you to use the service information described previously to perform these actions.

Costs of Compliance

How many airplanes would this proposed AD impact? We estimate that this proposed AD affects 397 airplanes in the U.S. registry.

What would be the cost impact of this proposed AD on owners/operators of the affected airplanes? We estimate the following costs to do the proposed inspection:

X

Labor cost	Parts cost	Total cost per airplane	Total cost on U.S. operators
1 work hour × $65 per hour = $65	N/A	$65	$65 × 397 = $25,805.

We estimate the following costs to do any necessary 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 replacement:

Labor cost	Parts cost	Total cost per airplane to replace all 8 barrel nuts
11 work hours × $65 per hour = $715	$60 for each barrel nut. There are 8 barrel nuts on each airplane Possible total cost of: $60 × 8 = $480.	$715 + $480 = $1,195.

Are there other actions that FAA is issuing that would present a cost impact on the MU-2B series airplane fleet? This is one of several actions that FAA is evaluating for unsafe conditions on the MU-2B airplanes. To date, this is the first proposed AD action to be taken.

Authority for This Rulemaking

What authority does FAA have for issuing this rulemaking action? 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

Would this proposed AD impact various entities? 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. See the ADDRESSES section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the Federal Aviation Administration 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 Federal Aviation Administration (FAA) amends § 39.13 by adding the following new airworthiness directive (AD):

Mitsubishi Heavy Industries, Ltd.: Docket No. FAA-2006-23578; Directorate Identifier 2006-CE-01-AD.

When Is the Last Date I Can Submit Comments on This Proposed AD?

(a) The FAA must receive comments on this AD action by February 27, 2006.

What Other ADs Are Affected by This Action?

(b) None.

What Airplanes Are Affected by This AD?

(c) This AD affects the following Mitsubishi Heavy Industries, Ltd. airplane models and serial numbers that are certificated in any category:

Model	Serial numbers
MU-2B-10	101 through 347 (Except 313 and 321).
MU-2B-15	101 through 347 (Except 313 and 321).
MU-2B-20	101 through 347 (Except 313 and 321).
MU-2B-25	101 through 347 (Except 313 and 321), 313SA, 321SA, and 348SA through 394SA.
MU-2B-26	101 through 347 (Except 313 and 321), 313SA, 321SA, and 348SA through 394SA.
MU-2B-26A	313SA, 321SA, and 348SA through 394SA.
MU-2B-30	501 through 696 (Except 652 and 661).
MU-2B-35	501 through 696 (Except 652 and 661), 652SA, 661SA, and 697SA through 730SA.
MU-2B-36	501 through 696 (Except 652 and 661), 652SA, 661SA, and 697SA through 730SA.
MU-2B-36A	652SA, 661SA, and 697SA through 730SA.

What Is the Unsafe Condition Presented in This AD?

(d) This AD results from a recent safety evaluation that used a data-driven approach to evaluate the design, operation, and maintenance of the MU-2B series airplanes in order to determine their safety and define what steps, if any, are necessary to ensure their safe operation. Part of that evaluation was to identify unsafe conditions that exist or could develop on the affected type design airplanes. The actions specified in this AD are intended to detect and correct cracks, corrosion, fractures, and incorrect torque values in the wing attach barrel nuts, which could result in failure of the wing barrel nuts and/or associated wing attachment hardware. This failure could lead to in-flight separation of the outer wing from the center wing section and result in loss of controlled flight.

What Must I Do To Address This Problem?

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

Actions	Compliance	Procedures
(1) Remove each wing attach barrel nut, bolt, and retainer and do a detailed visual inspection for cracks, corrosion, and fractures	Within the next 200 hours time-in-service (TIS) or 12 months after the effective date of this AD, whichever occurs first, unless already done	Follow Mitsubishi Heavy Industries, Ltd. MU-2 Service Bulletins referenced as JCAB T.C.: No. 241, dated July 14, 2004, and FAA T.C.: No. 103/57-004, dated August 2, 2004, as applicable.
(2) If any signs of cracks, corrosion, or fractures are found on any wing attach barrel nut during the inspection required in paragraph (e)(1) of this AD, replace that wing attach barrel nut, bolt, and retainer with new parts and install to the correct torque value	Before further flight after the inspection required in paragraph (e)(1) of this AD, unless already done	Follow Mitsubishi Heavy Industries, Ltd. MU-2 Service Bulletins referenced as JCAB T.C.: No. 241, dated July 14, 2004, and FAA T.C.: No. 103/57-004, dated August 2, 2004, as applicable, and the appropriate maintenance manual.
(3) If no signs of cracks, corrosion, or fractures are found during the inspection required in paragraph (e)(1) of this AD, you may reuse the barrel nuts and bolts if they have been inspected and are free of deformation and irregularities in the threads. Reinstall inspected parts to the correct torque value. If the barrel nuts and bolts are not free of deformation and irregularities in the threads, install new parts to the correct torque value	Before further flight after the inspection required in paragraph (e)(1) of this AD, unless already done	Follow Mitsubishi Heavy Industries, Ltd. MU-2 Service Bulletins referenced as JCAB T.C.: No. 241, dated July 14, 2004, and FAA T.C.: No. 103/57-004, dated August 2, 2004, as applicable, and the appropriate maintenance manual.

May I Request an Alternative Method of Compliance?

(f) The Manager, Fort Worth Airplane Certification Office, FAA, has the authority to approve alternative methods of compliance for this AD, if requested using the procedures found in 14 CFR 39.19.

(g) For information on any already approved alternative methods of compliance or for information pertaining to this AD, contact Andrew McAnaul, Aerospace Engineer, ASW-150 (c/o MIDO-43), 10100 Reunion Place, Suite 650, San Antonio, Texas 78216; telephone: [phone]; facsimile: [phone].

Is There Other Information That Relates to This Subject?

(h) Mitsubishi Heavy Industries, Ltd. MU-2 Service Bulletins JCAB T.C.: No. 241, dated July 14, 2004, and FAA T.C.: No. 103/57-004, dated August 2, 2004, pertain to the subject of this AD.

May I Get Copies of the Documents Referenced in This AD?

(i) To get copies of the documents referenced in this AD, contact Mitsubishi Heavy Industries, Ltd., Nagoya Aerospace Systems Works, 10, OYE-CHO, Minato-Ku, Nagoya, Japan, or Turbine Aircraft Services, Inc., 4550 Jimmy Doolittle Drive, Addison, Texas 75001; telephone: [phone]; facsimile: [phone]. To view the AD docket, go to the Docket Management Facility; U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, Washington, DC, or on the Internet at http://dms.dot.gov. The docket number is Docket No. FAA-2006-23578; Directorate Identifier 2006-CE-01-AD.

Issued in Kansas City, Missouri, on January 19, 2006.

John R. Colomy,

Acting Manager, Small Airplane Directorate, Aircraft Certification Service.