Daily Rules, Proposed Rules, and Notices of the Federal Government
On July 24, 2006, 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 RAC Beech Models 45 (YT-34), A45 (T-34A, B45), and D45 (T-34B) airplanes. That proposal was published in the
We provided the public the opportunity to participate in developing this AD. The following presents the comments received on the proposal and FAA's response to each comment:
Larry Bierma, Joe Enzminger, John Aldous, Michael Vadeboncoeur, John Rippinger, William E. Mayher, Dan Thomas, and Victor Barrett state that the inspection compliance in the proposed AD is a duplication of the inspection for those who have done the eddy current inspection recently as part of compliance with an alternative method of compliance (AMOC) to AD 2004-25-51.
The commenters state that requiring another eddy current inspection within 6 months after the effective date of this AD would be unnecessary and economically burdensome for those who have already done it. The commenters request credit for the last inspection done in compliance with an AMOC to AD 2004-25-51 as compliance for the initial inspection required in the proposed AD.
We have rewritten the compliance time to give full credit for previously accomplished eddy current inspections done in the area affected by this AD.
Michael Vadeboncoeur, John Aldous, Mike Talbot, Eric Evans, Earle Parks, Floyd Stilwell, Dan Thomas, Stephen Baksa, William Beitler, and Terrance Brennan state that, since the time AD 62-24-01 was issued, there have not been any accidents as a result of cracks in the horizontal stabilizer. The commenters request the proposed AD be withdrawn.
The commenters also request that stabilizer spars modified by Parks Industries supplemental type certificate (STC) either be exempt from the inspections or the inspection interval be increased to 1,000 hours TIS.
We do not agree with the commenters. In 2005, 148 of the affected airplanes were eddy current inspected. Cracks in the stabilizer spars and/or spar webs were found on 6 of these airplanes, which required the spars to be replaced. If no eddy current inspections had been done, those cracks may have grown and reached critical crack lengths, which could have compromised the integrity of the spar structure.
In order to increase the inspection interval or eliminate the spar inspections, we need supporting engineering analysis data regarding fatigue life, crack growth rate, etc. We have not received such data for the spars modified by the Parks Industries STC.
If we receive engineering analysis data that supports increasing the inspection intervals or eliminating the inspections, we may take additional rulemaking action at that time.
We are not changing the final rule AD action based on these comments.
Floyd Stilwell, Earle Parks, and Terrance Brennan state that the surface eddy current inspection is expensive and inconvenient. Qualified technicians to do the surface eddy current inspections have to be brought to the repair station from other parts of the country, which contributes to the expense of doing the eddy current inspection. The commenters request retaining the dye penetrant inspection.
We do not agree with the commenters. AD 2001-13-18 R1 currently requires owners/operators of all Beech Models 45 (YT-34), A45 (T-34A, B-45), and D45 (T-34B) airplanes to do repetitive 80-hour TIS eddy current inspections of the wing spar assemblies and other components following Raytheon Aircraft Mandatory ServiceBulletin No. SB 57-3329, Part II, Page 3/65, Issued: February, 2000. If the wing spar and stabilizer spar inspections are properly planned, these two inspections could be done at the same time. This planning would eliminate any extra expenses.
We have reason to believe that damage tolerance analysis of the stabilizer spar is being conducted by some owners. This may result in additional rulemaking action that could eliminate the inspection or increase the inspection interval. Until that time, AMOCs for this AD may be approved, if requested using the procedures found in 14 CFR 39.19.
We are not changing the final rule AD action based on these comments.
Dan Thomas, William Beitler, Floyd Stilwell, William Mayher, and Mike Talbot state that the eddy current inspection method is no better than the dye penetrant method for detecting cracks. The level of safety will not be enhanced by changing the inspection methods. Further, the eddy current method could produce false positives and the frequent inspections could also incur damage to the stabilizer spar. The commenters request the method of inspection be at the owner's/operator's option.
We do not agree with the commenters. The eddy current inspection method is a more sensitive inspection process. The dye penetrant inspection method at times could completely miss detecting the cracks.
All inspection methods have some inherent drawbacks. Eddy current inspection methods detect small surface cracks better than dye penetrant methods, and eddy current inspection methods are also capable of detecting subsurface cracks. Detection of cracks early is a definite advantage. Eddy current inspection methods could occasionally produce false positives; however, this could be avoided if cracks are confirmed by repeatable flaw indications.
If the inspections required by this AD are carefully done by qualified technicians, any damage to the spars could be prevented.
The 500-hour TIS repetitive inspection interval is a long interval between inspections for this type of airplane, which normally will take place once in 5 years or longer in most cases; therefore, we do not consider this inspection requirement as frequent.
We are not changing the final rule AD action based on this comment.
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.
We estimate that this AD affects 475 airplanes in the U.S. registry.
We estimate the following costs to accomplish each inspection:
We estimate the following costs to do any necessary horizontal stabilizer replacements that will be required based on the results of the inspection. We have no way of determining the number of airplanes that may need this replacement:
The only difference between this AD and AD 62-24-01 is the change of inspection method. There may be some minimal additional cost involved in doing the eddy current inspection because of possible equipment rentals necessary. No additional actions are being required. We have determined that this AD action does not increase the cost impact over that already required by AD 62-24-01.
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.
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 and responsibilities among the various levels of government.
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
Air transportation, Aircraft, Aviation safety, Safety.
49 U.S.C. 106(g), 40113, 44701.
(a) This AD becomes effective on April 16, 2007.
(b) This AD supersedes AD 62-24-01, Amendment 39-508.
(c) This AD affects the following airplane models and serial numbers that are certificated in any category:
(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/or rear horizontal stabilizer spars caused by fatigue cracks. This failure could result in stabilizer separation and loss of control of the airplane.
(e) 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, unless already done, as follows:
(f) The Manager, Wichita Aircraft Certification Office, FAA, ATTN: T.N. Baktha, Aerospace Engineer, 1801 Airport Road, Mid-Continent Airport, Wichita, Kansas 67209;
(g) AMOCs approved for AD 62-24-01 are approved for this AD.
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.
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 1
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.