06-6581. Airworthiness Directives; Raytheon Aircraft Company Beech Models 45 (YT-34), A45 (T-34A, B-45), and D45 (T-34B) Airplanes

AGENCY:

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

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

We propose to supersede Airworthiness Directive (AD) 62-24-01, which applies to all Raytheon Aircraft Company (Raytheon) Beech Models 45 (YT-34), A45 (T-34A, B45), and D45 (T-34B) airplanes. AD 62-24-01 currently requires you to repetitively inspect, using the dye penetrant method, the front and rear horizontal stabilizer spars for cracks and replace any cracked stabilizer. Since we issued AD 62-24-01, we determined that using dye penetrant inspection method may not detect cracks before failure of the horizontal stabilizer spars. Therefore, we are proposing to require the surface eddy current inspection method to detect cracks in the horizontal stabilizer spars. Consequently, this proposed AD would retain the actions required in AD 62-24-01 and change the required inspection method from dye penetrant to surface eddy current. We are proposing this AD to prevent failure of the front and rear horizontal stabilizer spars caused by fatigue cracks. This failure could result in stabilizer separation and loss of control of the airplane.

DATES:

We must receive comments on this proposed AD by September 29, 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.
• Governmentwide 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 20590-0001.
• 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.

FOR FURTHER INFORMATION CONTACT:

T.N. Baktha, Aerospace Engineer, FAA, Wichita Aircraft Certification Office, 1801 Airport Road, Mid-Continent Airport, Wichita, Kansas 67209; telephone: [phone]; facsimile: [phone].

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-2006-25105; Directorate Identifier 2006-CE-33-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 we receive concerning this proposed AD.

Discussion

Fatigue cracks found in the horizontal stabilizer spars caused us to issue AD 62-24-01, Amendment 39-508. AD 62-24-01 currently requires the following on all Raytheon Beech Models 45 (YT-34), A45 (T-34A, B45), and D45 (T-34B) airplanes:

• Repetitive inspections, using the dye penetrant method at 500-hour time-in-service (TIS) intervals, of the front and rear horizontal stabilizer spars between the butt rib and the inboard end for cracks; and
• Replacement of the horizontal stabilizer if cracks are found in either spar or the reinforcing doubler.

Investigation of a T-34 series airplane accident where the wing separated in flight revealed fatigue cracks in the stabilizer spar root sections. These spar root sections were inspected for fatigue cracks using the dye penetrant method (as required by AD 62-24-01) just 281 hours TIS before the fatal accident.

Since 281 hours TIS is much shorter than the 500-hour TIS inspection interval required by this AD, we have determined that using dye penetrant inspection method may not detect cracks before failure of the horizontal stabilizer spars. Therefore, we are proposing to require the surface eddy current inspection method to detect cracks in the horizontal stabilizer spars.

This condition, if not corrected, could result in failure of the horizontal stabilizer spars caused by fatigue cracks, which could result in stabilizer separation and loss of control of the airplane.

FAA's Determination and Requirements of This 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 supersede AD 62-24-01 with a new AD that would retain the actions required in AD 62-24-01 and only change the inspection procedure from the dye penetrant method to the surface eddy current method.

Costs of Compliance

We estimate that this proposed AD would affect 475 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
8 work-hours × $80 per hour = $640	Not applicable	$640	$640 × 475 = $304,000.

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
4 work-hours × $80 per hour = $320	$3,500	$320 + $3,500 = $3,820.

Cost Difference Between This Proposed AD and AD 62-24-01

The only difference between this proposed AD and AD 62-24-01 is the proposed change of inspection method. There may be some minimal additional cost involved in doing the proposed eddy current inspection because of possible equipment rentals necessary. No additional actions are being proposed. We have determined that this proposed AD action does not increase the cost impact over that already required by AD 62-24-01.

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://dms.dot.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
• 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 removing Airworthiness Directive (AD) 62-24-01, Amendment 39-508, and adding the following new AD:

Raytheon Aircraft Company: Docket No. FAA-2006-25105; Directorate Identifier 2006-CE-33-AD.

Comments Due Date

(a) We must receive comments on this airworthiness directive (AD) action by September 29, 2006.

Affected ADs

(b) This AD supersedes AD 62-24-01, Amendment 39-508.

Applicability

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

Model	Serial numbers
Beech 45 (YT-34)	All.
Beech A45 (T34A, B-45)	All.
Beech D45 (T-34B)	All.

Unsafe Condition

(d) This AD results from our determination that the surface eddy current inspection method should be used in place of the dye penetrant inspection method currently required in AD 62-24-01. We are issuing this AD to prevent failure of the front and rear horizontal stabilizer spars caused by fatigue cracks. This failure could result in stabilizer separation and loss of control of the airplane.

Compliance

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

Actions	Compliance	Procedures
(1) Using the surface eddy current inspection procedures outlined in the appendix of this AD, inspect the front and rear horizontal stabilizer spars between the butt rib and the inboard end for cracks	At the next repetitive inspection interval required by AD 62-24-01 or within the next 6 months after the effective date of this AD, whichever occurs first. Repetitively inspect thereafter at intervals not to exceed 500 hours time-in-service	The surface eddy current inspection procedures are contained in the appendix to this AD.
(2) If any crack is found in either spar or the reinforcing doubler during any inspection required in paragraph (e)(1) of this AD, replace the stabilizer	Before further flight after the inspection in which the crack is found. After the replacement, continue with the repetitive inspection requirement in paragraph (e)(1) of this AD	Not applicable.

Alternative Methods of Compliance (AMOCs)

(f) The Manager, Wichita Aircraft Certification Office (ACO), FAA, ATTN: T.N. Baktha, Aerospace Engineer, Wichita ACO, 1801 Airport Road, Mid-Continent Airport, Wichita, Kansas 67209; telephone: [phone]; facsimile: [phone], has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19.

(g) AMOCs approved for AD 62-24-01 are approved for this AD.

Related Information

(h) 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-2006-25105; Directorate Identifier 2006-CE-33-AD.

Appendix to Docket No. FAA-2006-25105

Surface Eddy Current Inspection Procedure

Note:

This surface eddy current inspection procedure is based on T-34 Spar Corporation TSC 3506, Rev C, dated May 10, 2005. The T-34 Spar Corporation is allowing the use of this procedure to be included in this Airworthiness Directive. Alternative methods of compliance procedures will be allowed, if approved by the Wichita Aircraft Certification Office and requested using the procedures found in 14 CFR 39.19.

Purpose

This procedure is to be used to detect cracks in the inner and outer spars of the front and rear spar assemblies of Raytheon Aircraft Company Beech Models 45 (YT-34), A45 (T-34A, B-45), and D45 (T-34B) airplane stabilizers outside of the steel bushings in the attach holes.

Area To Be Inspected

To access the area of inspection, remove the stabilizer from the airplane. The areas to be inspected include the forward and aft surfaces of the inner and outer front and rear spars of the horizontal stabilizers in the areas surrounding each of the attach holes.

Preparing the Area for Inspection

Thoroughly clean area to be inspected with solvent (acetone or equivalent) as required until no signs of dirt, grime, or oil remain on the front and rear spars from the closeout former inboard on the forward and aft surfaces of the spars.

Surfaces to be inspected should be smooth and corrosion-free. Any loss of thickness due to corrosion below material thickness tolerance is cause for rejection of the structure. An ultrasonic tester may be used to determine if material thickness has been compromised.

Equipment Requirements

Nortec Stavely 2000D Eddy Current Tester or equivalent.

Probe: 50-500 KHz, shielded, absolute, 0.071″ diameter (0.090 max. diameter), right angle, pencil style, surface probe, 5″ long, 1/2″ drop or equivalent. Use 0.025″ notch (beyond head) for calibration

Personal Requirements

Technicians with Eddy Current, Level II or Level III per one of the following specifications: ATA specification 105, SNT-TC-1A, or NAS-410 (MIL-std 410E).

Methods

Typical Set-up Parameters:

Frequency −350 KHz, Gain Vertical −75 dB, Horizontal −69 dB, Drive-Mid, Filters-Lo Pass-30, Hi Pass-0, Lift off-Horizontal to the left, adjust as required. The most reliable indication (minimum of 11/2 to 2 graticules) of the smallest observable flaw in the coupon (see attach Figures) occurs from the notch extending 0.025″ past the edge of the nominal fastener head (total notch length of 0.100″ from the edge of the nominal hole). Install appropriate aluminum guide pin into bushing such that the edge of the guide pin is flush with the edge of the bushing. Using the pin (see the attached Figures) as a guide, circle the area surrounding the steel bushing with the probe and adjacent area (approximately 1/4″) to inspect for cracks. Inspect forward and aft surfaces surrounding bushings of each spar.

Note:

T-34 Spar Corporation, 2800 Airport Road, Hanger A, Ada, Oklahoma, 74820 is a source for these coupons and pin.

Accept/Reject Criteria

Any repeatable flaw indication is cause for rejection in accordance with the procedure. In the event that any crack is detected, describe the flaw in detail providing sketch as needed and send the information to the Wichita ACO.

Documentation Requirements

Record inspection findings in the aircraft logbook.

Issued in Kansas City, Missouri, on July 24, 2006.

James E. Jackson,

Acting Manager, Small Airplane Directorate, Aircraft Certification Service.