E7-22939. Airworthiness Directives; Boeing Model 727 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 Boeing Model 727 airplanes. This proposed AD would require repetitive inspections for cracking or corrosion of the threaded end of the lower segment of the main landing gear (MLG) side strut, and corrective actions if necessary. This proposed AD also would require prior or concurrent inspection for cracking or corrosion of the threads and thread relief area of the lower segment, corrective action if necessary, and re-assembly using corrosion inhibiting compound. This proposed AD results from reports of the threads cracking on the MLG side strut lower segment. We are proposing this AD to prevent a fractured side strut, which could result in collapse of the MLG.

DATES:

We must receive comments on this proposed AD by January 10, 2008.

ADDRESSES:

You may send comments by any of the following methods:

• 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 AD, contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.

Examining the AD Docket

You may examine the AD docket 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 AD docket contains this proposed AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Office (telephone [phone]) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT:

Berhane Alazar, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or arguments about this proposed AD. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2007-0227; Directorate Identifier 2007-NM-159-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this proposed AD. We will consider all comments received by the closing date and may amend this proposed AD because 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 about this proposed AD.

Discussion

We have received many reports of the threads cracking on the main landing gear (MLG) side strut lower segment, on Boeing Model 727 airplanes. In one instance an operator reported hearing a loud noise during taxiing after landing. The subsequent inspection revealed the MLG side strut was broken at the threaded end of the lower segment, causing the side strut to become detached from the shock strut. This condition, if not corrected, could result in collapse of the MLG.

Relevant Service Information

We have reviewed Boeing Special Attention Service Bulletin 727-32-0338, Revision 4, dated April 7, 2007. The service bulletin describes procedures for repetitive detailed and magnetic particle inspections for cracking or corrosion of the threaded end of the lower segment of the MLG side strut. The service bulletin also describes procedures for corrective actions for corrosion or cracking. The corrective actions include replacing the part with a serviceable part, repairing the part as given in the Boeing Model 727 Overhaul Manual (OHM) 32-13-01, and doing a modification of the lower segment. There are five configurations for modification:

• Option I Configuration—Blending out cracks and doing thread root radiusing. This modification applies only to airplanes with maximum taxi gross weight of 191,000 pounds and below.
• Option II Configuration—Installing a new retainer nut, locknut, lock washer, and seals. This modification applies only to airplanes on which the segment is crack-free.
• Option III Configuration—Removing 0.8-inch of the lower end of the lower segment, inserting a spacer, and replacing the retainer nut, locknut, lock washer, and seals.
• Option IV Configuration—Similar to Option III, but also removing additional lubrication on the retainer nut; and applying corrosion inhibiting compound, rather than grease, to the threads at re-assembly.
• Option V Configuration—Replacing the side strut lower segment with a larger-diameter spare (not production) part that has fatigue improvement on the threads.

Boeing Special Attention Service Bulletin 727-32-0338, Revision 4, also recommends the prior or concurrent accomplishment of the actions specified in the table titled “Prior/Concurrent Service Bulletins.” The prior/concurrent service bulletins facilitate the overhaul and repair procedures specified in Boeing Special Attention Service Bulletin 727-32-0338, Revision 4.

Prior/Concurrent Service Bulletins

For—	Boeing 727 service bulletin—	Describes procedures for these prior or concurrent actions—
All airplanes	727-32-0411, Revision 1, dated February 19, 2007	Inspecting for corrosion or cracking of the threads and thread relief area of the swivel clevis, and improving the corrosion protection of the swivel clevis fitting threads in commonly affected airplanes.
Airplanes specified as Options III, IV and V configurations in Boeing Special Attention Service Bulletin 727-32-0338, Revision 4	32-79, Revision 1, dated February 27, 1967	Modifying the MLG side strut universal joint.
	32-157, dated August 30, 1968	Replacing the MLG side strut swivel bushing, incorporating only Parts Kit 65-89855-1, and not installing the lube fitting in the lower segment.
Airplanes specified as Option V configuration in Boeing Special Attention Service Bulletin 727-32-0338, Revision 4	727-32-268, Revision 2, dated February 20, 1981	Inspecting and modifying the MLG side strut.
	727-57-163, dated September 17, 1982	Resolving the interference between the MLG gear beam and the MLG side strut.

Boeing Special Attention Service Bulletin 727-32-0338, Revision 4, specifies that where any assembly, lubrication, or corrosion protection procedure in a prior/concurrent service bulletin differs from those in Boeing Special Attention Service Bulletin 727-32-0338, Revision 4, operators should use the procedures in Boeing Special Attention Service Bulletin 727-32-0338, Revision 4.

Accomplishing the actions specified in the service information is intended to adequately address the unsafe condition.

FAA's Determination and Requirements of the Proposed AD

We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other airplanes of this same type design. For this reason, we are proposing this AD, which would require accomplishing the actions specified in the service information described previously.

Costs of Compliance

There are about 842 airplanes of the affected design in the worldwide fleet. This proposed AD would affect about 459 airplanes of U.S. registry. The following table provides the estimated costs for U.S. operators to comply with this proposed AD. The average labor rate is $80 per work hour.

Estimated Costs

Action	Work hours	Average labor rate per hour	Cost per airplane	Fleet cost
Inspection	12	$80	$960, per inspection cycle	$440,640, per inspection cycle.
Prior/concurrent actions	Up to 6	$80	Up to $480	Up to $220,320.

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. 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 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 Federal Aviation Administration (FAA) amends § 39.13 by adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2007-0227; Directorate Identifier 2007-NM-159-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by January 10, 2008.

Affected ADs

(b) None.

Applicability

(c) This AD applies to all Model 727, 727C, 727-100, 727-100C, 727-200, and 727-200F series airplanes, certificated in any category.

Unsafe Condition

(d) This AD results from reports of the threads cracking on the main landing gear (MLG) side strut lower segment. We are issuing this AD to prevent a fractured side strut, which could result in collapse of the MLG.

Compliance

(e) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.

Inspections and Corrective Actions

(f) At the latest applicable time in paragraph (f)(1), (f)(2), or (f)(3) of this AD: Do detailed and magnetic particle inspections for cracking or corrosion of the threaded end of the lower segment of the MLG side strut and do all applicable corrective actions as specified in the Accomplishment Instructions of Boeing Special Attention Service Bulletin 727-32-0338, Revision 4, dated April 7, 2007. Do all applicable corrective actions before further flight. Repeat the inspection thereafter at intervals not to exceed 120 months.

(1) Within 48 months after the last MLG overhaul.

(2) Within 6 months after the effective date of this AD.

(3) Within 120 months after the last MLG overhaul for airplanes on which the actions in Boeing Special Attention Service Bulletin 727-32-0338, Revision 4, dated April 7, 2007, have been accomplished before the effective date of this AD.

Prior/Concurrent Requirements

(g) Prior to or concurrently with the actions required by paragraph (f) of this AD: Do all applicable actions specified in the service bulletins listed in Table 1 of this AD. Where the lubrication and corrosion protection procedures in any service bulletin listed in Table 1 of this AD differ from those in Boeing Special Attention Service Bulletin 727-32-0338, Revision 4, dated April 7, 2007, use the procedures in Boeing Special Attention Service Bulletin 727-32-0338, Revision 4.

Table 1.—Prior/Concurrent Requirements

For—	Boeing 727 service bulletin—	Describes procedures for these prior or concurrent actions—
(1) All airplanes	727-32-0411, Revision 1, dated February 19, 2007	Inspecting for corrosion or cracking of the threads and thread relief area of the swivel clevis, and improving the corrosion protection of the swivel clevis fitting threads in commonly affected airplanes.
(2) Airplanes specified as Options III, IV and V configurations in Boeing Special Attention Service Bulletin 727-32-0338, Revision 4	32-79, Revision 1, dated February 27, 1967	Modifying the MLG side strut universal joint.
	32-157, dated August 30, 1968	Replacing the MLG side strut swivel bushing, incorporating only Parts Kit 65-89855-1, and not installing the lube fitting in the lower segment.
(3) Airplanes specified as Option V configuration in Boeing Special Attention Service Bulletin 727-32-0338, Revision 4	727-32-268, Revision 2, dated February 20, 1981	Inspecting and modifying the MLG side strut.
	727-57-163, dated September 17, 1982	Resolving the interference between the MLG gear beam and the MLG side strut.

Alternative Methods of Compliance (AMOCs)

(h)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.

(2) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. 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.

(3) An AMOC that provides an acceptable level of safety may be used for any repair required by this AD, if it is approved by an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization Organization who has been authorized by the Manager, Seattle ACO, to make those findings. For a repair method to be approved, the repair must meet the certification basis of the airplane, and the approval must specifically refer to this AD.

Issued in Renton, Washington, on November 13, 2007.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.