SUPPLEMENTARY INFORMATION:

Discussion

What events have caused this AD? The FAA has received several reports of rudder tube and rib corrosion on Piper PA-31 Series airplanes. The area surrounding the rudder torque tube assembly and rudder rib does not have a means or access to inspect in this area and neither means nor exits for water to drain out.

What is the potential impact if FAA took no action? Corrosion in the rudder torque tube assembly and rudder rib could result in failure of the rudder torque tube. This failure could lead to loss of rudder control.

Has FAA taken any action to this point? 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 Piper Models PA-31, PA-31-300, PA-31-325, PA-31-350, PA-31P, PA-31T, PA-31T1, PA-31T2, PA-31T3, and PA-31P-350 airplanes. This proposal was published in the Federal Register as a notice of proposed rulemaking (NPRM) on June 3, 2003 (68 FR 33030). The NPRM proposed to require you to install an inspection hole, conduct a detailed visual inspection of the rudder torque tube and associated ribs for corrosion, and, if corrosion is found, replace the rib/rudder torque tube assembly.

Comments

Was the public invited to comment? We provided the public the opportunity to participate in the development of this AD. The following presents the comments received on the proposal and FAA's response to each comment:

Comment Issue No. 1: Extend the Compliance Time

What is the commenter's concern? A commenter recommends extending the compliance time from 100 hours time-in-service (TIS) to 150 hours TIS. The commenter states that the extension is necessary due to a reported lack of parts and the difficulty in scheduling involved with AD compliance.

What is FAA's response to the concern? The FAA agrees that 150 hours TIS would be a more realistic compliance time.

We are changing the final rule AD action accordingly.

Comment Issue No. 2: Allow Option to Repair Parts

What is the commenter's concern? The commenter recommends the following: if you find “light corrosion” or “corrosion that could significantly weaken the rib/rudder torque tube assembly that is less than 50 percent of the thickness over an area less than two square inches' then you may clean up, repair, and coat the corroded area to prevent further damage and continue the part in service.

What is FAA's response to the concern? The FAA is currently unaware of any approved repair design for the rib/rudder torque tube assembly. However, FAA has no objection to operation of aircraft with parts that have been repaired or reworked per an FAA-approved repair design.

Therefore, we are changing the final rule AD action to provide the option of repairing with an FAA-approved design.

Comment Issue No. 3: Special Flight Permits Are Not Addressed in the NPRM

What is the commenter's concern? The commenter states that since special flight permits are not addressed in the NPRM, the current 14 CFR part 39 applies and that there is no restriction against issuing a special flight permit.

What is FAA's response to the concern? On July 10, 2002, the FAA published a new version of 14 CFR part 39 (67 FR 47997, July 22, 2002), which governs the FAA's AD system. This regulation now includes material that ( printed page 67589) relates to special flight permits. This material previously was included in each individual AD. Since this material is included in 14 CFR part 39, we did not include it in this AD action.

We are not making any changes to the final rule AD action.

Comment Issue No. 4: Allow an Alternate Method of Inspection

What is the commenter's concern? The commenter suggests an alternative to installing an inspection hole in the rudder skin for the rudder torque tube assembly. This alternative method of inspection is to use the tooling hole in the rudder bottom rib since this is convenient and does not contribute to corrosion. Further, you could enlarge the tooling hole to ease use of inspection tools.

What is FAA's response to the concern? The FAA agrees that the proposed alternative use of the tooling hole (with optional enlargement) in the rudder bottom rib is an acceptable substitute to installing an access hole.

We are changing the final rule AD action accordingly.

Comment Issue No. 5: Allow Application of Corrosion Inhibitor

What is the commenter's concern? The commenter recommends allowing application of rust inhibitor compound.

What is FAA's response to the concern? The application of rust inhibitor compound to the contact surfaces is identified in Piper Service Bulletin No. 1105A, dated September 22, 2003. As a minor correction, we are also noting to protect bare metal per Section 8, FAA Advisory Circular (AC) 43.13-1B.

We are incorporating the referenced correction in the final rule AD action.

Conclusion

What is FAA's final determination on this issue? We have carefully reviewed the available data and determined that air safety and the public interest require adopting the AD as proposed except for the changes discussed above and minor editorial corrections. We have determined that these changes and 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.

Changes to 14 CFR Part 39—Effect on the AD

How does the revision to 14 CFR part 39 affect this AD? On July 10, 2002, the FAA published a new version of 14 CFR part 39 (67 FR 47997, July 22, 2002), which governs the FAA's AD system. This regulation now includes material that relates to altered products, special flight permits, and alternative methods of compliance. This material previously was included in each individual AD. Since this material is included in 14 CFR part 39, we will not include it in future AD actions.

Costs of Compliance

How many airplanes does this AD impact? We estimate that this AD affects 2,269 airplanes in the U.S. registry.

What is the cost impact of this AD on owners/operators of the affected airplanes?

We estimate the following costs to accomplish the installation of inspection and drain holes and inspection of torque tube and associated ribs for corrosion:

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

Regulatory Findings

Will this AD impact various entities? 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.

Will this AD involve a significant rule or regulatory action? 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 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 “2003-CE-03-AD” in your request.

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:

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

2. FAA amends § 39.13 by adding a new AD to read as follows:

( printed page 67590)

2003-24-07 The New Piper Aircraft, Inc.: Amendment 39-13376; Docket No. 2003-CE-03-AD.

When Does This AD Become Effective?

(a) This AD becomes effective on February 9, 2004.

What Other ADs Are Affected by This Action?

(b) None.

What Airplanes Are Affected by This AD?

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

What Is the Unsafe Condition Presented in This AD?

(d) This AD is the result of reports of rudder tube corrosion. The actions specified by this AD are intended to detect and correct corrosion in the rudder torque tube assembly and rudder rib, which could result in failure of the rudder torque tube. This failure could lead to loss of rudder control.

What Must I Do to Address This Problem?

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

(f) All repairs must address the following:

(1) Detect hidden corrosion damage:

(i) In the faying surface between the rudder ribs and torque tube assembly attachments.

(ii) Inside the bore of the torque tube.

(2) Establish procedures for removing corrosion or for corrosion prevention of repaired parts. Advisory Circular (AC) 43.13-1B Acceptable Methods, Techniques, and Practices-Aircraft Inspection and Repair, and AC 43-4A, Corrosion Control for Aircraft, provide resources for establishment of these procedures.

(3) For repairs involving material removal without reinforcement: Define a clear, accurate, and complete description of negligible damage limits. Note that acceptable amounts of material removal may be location-dependent. Higher-stressed areas will be less tolerant of material removal.

(4) For all repairs involving reinforcement: A clear, accurate, and complete description of the repair design must be established per 14 CFR part 21.31.

(5) Verify that all repairs follow Subpart C—Strength Requirements and Subpart D—Design and Construction of Civil Aviation Regulations (CAR) 3, dated May 15, 1956 (the original certification basis for the Piper PA-31 Series as shown in type certificate data sheets A8EA and A20SO).

May I Request an Alternative Method of Compliance?

(g) You may request a different method of compliance or a different compliance time for this AD by following the procedures in 14 CFR 39.13. Send your request to the Manager, Atlanta Aircraft Certification Office (ACO), FAA. For information on any already approved alternative methods of compliance, contact William O. Herderich, Aerospace Engineer, FAA, Atlanta ACO, One Crown Center, 1895 Phoenix Boulevard, Suite 450, Atlanta, Georgia 30349; telephone: (770) 703-6082; facsimile: (770) 703-6097.

Does This AD Incorporate Any Material by Reference?

(h) You must do the actions required by this AD following the instructions in The New Piper Aircraft, Inc. Service Bulletin No. 1105A, dated September 22, 2003. The Director of the Federal Register approved the incorporation by reference of this service bulletin per 5 U.S.C. 552(a) and 1 CFR part 51. You may get a copy from The New Piper Aircraft, Inc., Customer Services, 2926 Piper Drive, Vero Beach, Florida 32960; telephone: (772) 567-4361; facsimile: (772) 978-6584. You may review copies at FAA, Central Region, Office of the Regional Counsel, 901 Locust, Room 506, Kansas City, Missouri 64106; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.