01-21224. Airworthiness Directives; Boeing Model 767 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain Boeing Model 767 series airplanes, that currently requires inspections and various follow-on actions to detect cracking and corrosion of the aft trunnion of the outer cylinder of the main landing gear (MLG). That action also requires termination of the inspections by repairing the outer cylinder and installing new aft trunnion bushings. This action would prohibit the use of a particular corrosion inhibiting compound during accomplishment of the terminating action. This action is necessary to prevent the collapse of the MLG due to stress corrosion cracking of the aft trunnion of the outer cylinder. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by September 24, 2001.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2001-NM-198-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal holidays. Comments may be submitted via fax to [phone]. Comments may also be sent via the Internet using the following address: [e-mail]. Comments sent via fax or the Internet must contain “Docket No. 2001-NM-198-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 for Windows or ASCII text.

The service information referenced in the proposed rule may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT:

John Craycraft, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this action may be changed in light of the comments received.

Submit comments using the following format:

• Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.
• For each issue, state what specific change to the proposed AD is being requested.
• Include justification (e.g., reasons or data) for each request.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2001-NM-198-AD.” The postcard will be date stamped and returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2001-NM-198-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

On October 10, 1996, the FAA issued AD 96-21-06, amendment 39-9783 (61 FR 55080, October 24, 1996), applicable to certain Boeing Model 767 series airplanes, to require inspections and various follow-on actions to detect cracking and corrosion of the aft trunnion of the outer cylinder of the main landing gear (MLG). That action also requires termination of the inspections by repairing the outer cylinder and installing new aft trunnion bushings. That action was prompted by reports of failure of several MLG due to fracture of the aft trunnion outer cylinder. The requirements of that AD are intended to prevent the collapse of the MLG due to stress corrosion cracking of the aft trunnion of the outer cylinder.

Actions Since Issuance of Previous Rule

Since the issuance of that AD, the airplane manufacturer has received reports indicating that a particular corrosion inhibiting compound has caused severe corrosion in the Model 767 MLG aft trunnion of the outer cylinder. The corrosion was found on MLGs that were previously reworked using Desoto 823E508 (Titanine JC5A) corrosion inhibiting compound during accomplishment of Boeing Alert Service Bulletin 767-32A0148, dated December 21, 1995, or Revision 1, dated October 10, 1996 (which were referenced in AD 96-21-06 as the appropriate source of service information for accomplishing the terminating action).

Over time, that particular corrosion inhibiting compound deteriorates and becomes hard and dry. If moisture enters the outer cylinder aft trunnion and mixes with Titanine JC5A, a series of chemical reactions occurs and the reaction products can degrade the primer and cadmium plating. This may lead to corrosion in the aft trunnion where Titanine JC5A was used. Such corrosion, if not corrected, could result in the collapse of the MLG due to stress corrosion cracking of the aft trunnion of the outer cylinder.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Service Bulletin 767-32A0148, Revision 2, dated November 30, 2000. This revised service bulletin is essentially identical to the original version and Revision 1 of the service bulletin. The only change effected by Revision 2 is to no longer allow the use of Desoto 823E508 (Titanine JC5A) as an option when incorporating that service bulletin. Revision 2 of the service bulletin adds Zip-Chem ZC-027L as an acceptable corrosion inhibiting compound. Zip-Chem ZC-027L and Mastinox 6856K are the only qualified BMS 3-27 products acceptable for use in incorporating that service bulletin. Accomplishment of the actions specified in the service bulletin is intended to adequately address the identified unsafe condition.

Explanation of Requirements of Proposed Rule

Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would supersede AD 96-21-06 to continue to require the actions specified by that AD. However, this proposed AD would prohibit the use of a particular corrosion inhibiting compound during accomplishment of the terminating action specified in AD 96-21-06. The actions would be required to be accomplished in accordance with the service bulletin described previously, as well as other service information specified in the existing AD.

Other Relevant Rulemaking

The manufacturer has issued a related service bulletin, Boeing Alert Service Bulletin 767-32A0192, dated May 31, 2001, which gives instructions for inspections of the MLG to detect corrosion or cracking; corrective actions, if necessary; application of an alternate corrosion inhibiting compound; and terminating action for the inspections and corrosion inhibiting compound, for airplanes on which Desoto 823E508 (Titanine JC5A) has been used. The FAA is considering the issuance of a separate rulemaking action to further address the identified unsafe condition on airplanes on which Desoto 823E508 (Titanine JC5A) was used.

Cost Impact

There are approximately 605 airplanes of the affected design in the worldwide fleet. The FAA estimates that 200 airplanes of U.S. registry would be affected by this proposed AD.

The actions that are currently required by AD 96-21-06 take approximately 252 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts cost approximately $9,510 per airplane. Based on these figures, the cost impact of the currently required actions on U.S. operators is estimated to be $4,926,000, or $24,630 per airplane.

The prohibition of a certain corrosion inhibiting compound proposed in this AD action would not change the cost impact on U.S. operators from that imposed by the superseded AD.

The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this proposed AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.

Regulatory Impact

The regulations proposed herein 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. Therefore, it is determined that this proposal would not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that this 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) if promulgated, 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. A copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend part 39 of the Federal Aviation Regulations (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. Section 39.13 is amended by removing amendment 39-9783 (61 FR 55080, October 24, 1996), and by adding a new airworthiness directive (AD), to read as follows:

Boeing: Docket 2001-NM-198-AD. Supersedes AD 96-21-06, amendment 39-9783.

Applicability: Model 767 series airplanes having line numbers 001 through 605 inclusive, on which the terminating action required by paragraph (e) of this AD has not been accomplished; certificated in any category.

Note 1:

This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (i)(1) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent collapse of the main landing gear (MLG) due to stress corrosion cracking of the aft trunnion of the outer cylinder, accomplish the following:

Note 2:

This AD is merely a restatement of the requirements of AD 96-21-06, amendment 39-9783, with one exception: Only Revision 2, dated November 30, 2000, of Boeing Service Bulletin 767-32A0148, which disallows the use of Desoto 823E508 (Titanine JC5A) corrosion inhibiting compound, may be used after the effective date of this new AD. As allowed by the phrase, “unless accomplished previously,” if those requirements of AD 96-21-06 have already been accomplished prior to the effective date of this AD in accordance with prior versions of that service bulletin, this AD does not require that those actions be repeated. The FAA is, however, considering the issuance of a separate rulemaking action to further address the identified unsafe condition on airplanes on which Desoto 823E508 (Titanine JC5A) was used.

Restatement of the Requirements of AD 96-21-06

Inspections and Various Follow-On Actions

(a) Perform the inspections described in paragraph III, Accomplishment Instructions, of Boeing Alert Service Bulletin 767-32A0151, dated November 30, 1995, or Revision 1, dated October 10, 1996, to detect cracking and corrosion of the aft trunnion of the outer cylinder of the MLG at the time specified in paragraph (a)(1), (a)(2), or (a)(3) of this AD, as applicable. These inspections are to be accomplished in accordance with Figure 1 of the alert service bulletin. Repeat these inspections thereafter at the intervals specified in that alert service bulletin. To determine the category in which an airplane falls, the age of the outer cylinder of the MLG is to be calculated as of February 16, 1996 (the effective date of AD 96-03-02 R1, amendment 39-9526). For airplanes on which the age of the right MLG differs from the age of the left MLG, an operator may place the airplane into a category that is the higher (numerically) of the two categories to ease its administrative burden, and to simplify the recordkeeping requirements imposed by this AD. Once the category into which an airplane falls is determined, operators must obtain approval from the Manager, Seattle Aircraft Certification Office (ACO), FAA, to move that airplane into another category.

Note 3:

The broken (dash) lines used in Figure 1 of Boeing Alert Service Bulletin 767-32A0151, dated November 30, 1995, and Revision 1, dated October 10, 1996, denote “go to” actions for findings of discrepancies detected during any of the inspections required by this AD.

Note 4:

Boeing Alert Service Bulletin 767-32A0151, dated November 30, 1995, and Revision 1, dated October 10, 1996, refer to Boeing Alert Service Bulletin 767-32A0148, dated December 21, 1995, and Revision 1, dated October 10, 1996, for procedures to repair the outer cylinder and replace the bushings in the outer cylinder of the MLG with new bushings.

(1) For airplanes identified as Category 3 in paragraph I.C. of Boeing Alert Service Bulletin 767-32A0151, dated November 30, 1995, or Revision 1, dated October 10, 1996: Perform the initial inspections within 30 days after February 16, 1996 (the effective date of AD 96-03-02 R1, amendment 39-9526).

(2) For airplanes identified as Category 2 in paragraph I.C. of Boeing Alert Service Bulletin 767-32A0151, dated November 30, 1995, or Revision 1, dated October 10, 1996: Perform the initial inspections within 90 days after February 16, 1996.

(3) For airplanes identified as Category 1 in paragraph I.C. of Boeing Alert Service Bulletin 767-32A0151, dated November 30, 1995, or Revision 1, dated October 10, 1996: Perform the initial inspections prior to the accumulation of 21/2 years since the MLG outer cylinder was new or last overhauled, or within 150 days after February 16, 1996, whichever occurs later.

(b) If no cracking or corrosion is detected during the inspections required by paragraph (a) of this AD, accomplish the follow-on actions described in Boeing Alert Service Bulletin 767-32A0151, November 30, 1995, or Revision 1, dated October 10, 1996, at the time specified in the alert service bulletin. These follow-on actions are to be accomplished in accordance with that alert service bulletin.

(c) If any cracking is detected during the inspections required by paragraph (a) of this AD, prior to further flight, replace the outer cylinder with a new or serviceable outer cylinder in accordance with Boeing Alert Service Bulletin 767-32A0151, dated November 30, 1995, or Revision 1, dated October 10, 1996.

(d) If any corrosion is detected during the inspections required by paragraph (a) of this AD, accomplish the follow-on actions at the time specified in the “Corrosion Flowchart,” in Figure 1 of Boeing Alert Service Bulletin 767-32A0151, dated November 30, 1995, or Revision 1, dated October 10, 1996. The follow-on actions are to be accomplished in accordance with that alert service bulletin.

Terminating Action

(e) Unless previously accomplished in accordance with paragraph (e) of AD 96-21-06, at the time specified in either paragraph (e)(1) or (e)(2) of this AD, as applicable, repair the outer cylinder and replace the bushings in the aft trunnion and crossbolt of the MLG with new bushings, in accordance with Boeing Service Bulletin 767-32A0148, Revision 2, dated November 30, 2000. Accomplishment of this repair and replacement constitutes terminating action for this AD, and for the requirements of AD 95-19-10, amendment 39-9372; and AD 95-20-51, amendment 39-9398.

Note 5:

Boeing Service Bulletin 767-32A0148, Revision 2, dated November 30, 2000, refers to Boeing Component Maintenance Manual (CMM) 32-11-40 for certain procedures.

(1) For airplanes identified as Category 3 in paragraph I.C. of Boeing Alert Service Bulletin 767-32A0151, dated November 30, 1995, or Revision 1, dated October 10, 1996: Accomplish the repair and replacement within 18 months after November 29, 1996 (the effective date of AD 96-21-06, amendment 39-9783).

(2) For airplanes identified as either Category 1 or Category 2 in paragraph I.C. of Boeing Alert Service Bulletin 767-32A0151, dated November 30, 1995, or Revision 1, dated October 10, 1996: Accomplish the repair and replacement at the time specified in either paragraph (e)(2)(i) or (e)(2)(ii) of this AD.

(i) Prior to the accumulation of 51/2 years since the MLG outer cylinders were new or last overhauled, or within 18 months after November 29, 1996, whichever occurs later; or

(ii) Prior to the accumulation of 7 years since the MLG outer cylinders were new or last overhauled, provided that accomplishment of visual and non-destructive testing (NDT) inspections at the times specified in Figure 1 of the Accomplishment Instructions of Boeing Alert Service Bulletin 767-32A0151, dated November 30, 1995, or Revision 1, dated October 10, 1996, are repeated until the repair and replacement are accomplished.

(f) Accomplishment of the inspection requirements of this AD (in accordance with Boeing Alert Service Bulletin 767-32A0151, dated November 30, 1995, or Revision 1, dated October 10, 1996) is considered acceptable for compliance with AD 95-19-10, amendment 39-9372; and AD 95-20-51, amendment 39-9398.

New Requirement of This AD

(g) As of the effective date of this AD, only Revision 2, dated November 30, 2000, of Boeing Service Bulletin 767-32A0148 shall be used to accomplish the actions required by paragraph (e) of this AD.

Use of Titanine JC5A Prohibited

(h) As of the effective date of this AD, no person shall use the corrosion inhibiting compound Desoto 823E508 (Titanine JC5A) on any airplane.

Alternative Methods of Compliance

(i)(1) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Seattle ACO. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO.

Note 6:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.

(2) Alternative methods of compliance, approved in accordance with AD 96-03-02, amendment 39-9497; AD 96-03-02 R1, amendment 39-9526; AD 95-19-10, amendment 39-9372; or AD 95-20-51, amendment 39-9398; are approved as alternative methods of compliance with this AD except as required in paragraph (h) of this AD.

Special Flight Permits

(j) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

Issued in Renton, Washington, on August 16, 2001.

Vi L. Lipski,

Manager, Transport Airplane Directorate, Aircraft Certification Service.