E8-13579. Airworthiness Directives; Boeing Model 767-200 and -300 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Supplemental notice of proposed rulemaking; reopening of comment period.

SUMMARY:

This document revises an earlier proposed airworthiness directive (AD), applicable to certain Boeing Model 767-200 and -300 series airplanes. That proposed rule would have required replacing certain door-mounted escape slides and slide-raft assemblies with new slide-raft assemblies; replacing certain escape system latches with new latches; and modifying or replacing certain counterbalance assemblies with new counterbalance assemblies; as applicable. This new action revises the proposed rule by extending the compliance time, adding requirements to install a longer firing cable and test the valve of the inflation trigger system of the slide-raft, and, for certain airplanes, adding procedures to adjust the door counter balance systems. The actions specified by this new proposed AD are intended to prevent the escape slides and slide-rafts of the forward and mid-cabin entry and service doors from being too steep for evacuation in the event that the airplane rotates onto the aft fuselage into the extreme tip-back condition. In the extreme tip-back condition, the forward and mid-cabin exits could result in steeper sliding angles, which could cause injury to passengers and crewmembers during an emergency evacuation. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by July 14, 2008.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2001-NM-237-AD, 1601 Lind Avenue, SW., Renton, Washington 98057-3356. Comments may be inspected at this location between 9 a.m. and 3 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-237-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 or 2000 or ASCII text.

The service information referenced in the proposed rule may be obtained from Boeing Commercial Airplanes, 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:

Keith Ladderud, Aerospace Engineer, Cabin Safety and Environmental Systems Branch, ANM-150S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; 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-237-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-237-AD, 1601 Lind Avenue, SW., Renton, Washington 98057-3356.

Discussion

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to add an airworthiness directive (AD), applicable to certain Boeing Model 767-200 and -300 series airplanes, was published as a notice of proposed rulemaking (NPRM) in the Federal Register on November 25, 2003 (68 FR 66026). That NPRM would have required replacing certain door-mounted escape slides and slide-raft assemblies with new slide-raft assemblies; replacing certain escape system latches with new latches; and modifying or replacing certain counterbalance assemblies with new counterbalance assemblies; as applicable. That NPRM was prompted by reports indicating that the original analysis of the highest sill heights for the forward and mid-cabin entry and service doors is no longer valid on certain Boeing Model 737-200 and -300 series airplanes. That condition, if not corrected, could result in injury to passengers and crewmembers during an emergency evacuation.

Actions Since Issuance of Previous Proposal

Since the issuance of that NPRM, we have received three reports of uncommanded deployments of the door-mounted escape slide inside the passenger cabin. The uncommanded inflation caused damage to a lavatory, ceiling panels, and doors. It has been determined that variability in packing the slide can result in excessive tension on the firing cable. Therefore, certain affected airplanes must have a longer firing cable installed, and the inflation trigger system must be tested. To accommodate this change, Boeing has issued the following service bulletins:

• Boeing Alert Service Bulletin 767-25A0266, Revision 2, dated September 27, 2007. We referred to Boeing Alert Service Bulletin 767-25-0266, dated September 14, 2000, as the appropriate source of service information for accomplishing the required actions in the original NPRM. In addition to the existing actions, Revision 2 of the service bulletin specifies procedures to adjust the door counterbalance systems for Group 1 and 2 airplanes (procedures were added in Boeing Alert Service Bulletin 767-25A0266, Revision 1, dated December 4, 2006). Revision 2 of the service bulletin also specifies that more work is necessary on airplanes changed in accordance with the procedures specified in the original release of the service bulletin. Revision 2 also includes a reference to the procedures in Boeing Alert Service Bulletin 767-25A0395, Revision 1, adds instructions for adjusting the door counterbalance system for certain airplanes, and corrects certain part numbers (P/Ns), among other changes.
• Boeing Alert Service Bulletin 767-25A0395, Revision 1, dated January 25, 2007. This service bulletin describes procedures for determining if a slide-raft with supplier P/N 5A3294-1, 5A3294-2, 5A3295-1, or 5A3295-3 (Boeing P/N S416T214-3, S416T214-4, S416T214-2, and S416T214-1, respectively), is installed. If those P/Ns are not installed, the service bulletin specifies that no further action is necessary. If any of those P/Ns are installed, the service bulletin provides procedures for lengthening the firing cable and testing the valve of the inflation trigger system of the escape slide-raft.

Boeing Alert Service Bulletin 767-25A0395, Revision 1, refers to Goodrich Service Bulletin 5A3294/5A3295-25-362, dated July 25, 2006, as an additional source of service information for lengthening the firing cable and testing the valve of the inflation trigger system of the escape slide-raft.

Comments

Due consideration has been given to the comments received in response to the original NPRM:

Support for the Original NPRM

Airline Pilots Association, International (ALPA) concurs with the corrective actions in the original NPRM.

Support for Replacement Parts

Goodrich Aircraft Interior Products states that it is prepared to support the need for replacement parts within the compliance time specified in the original NPRM.

Request To Clarify the Unsafe Condition

Boeing requests a change to the wording of the unsafe condition in the Summary and Discussion sections of the NPRM. Boeing states that the existing slide-rafts are not “too short to reach the ground” as stated in the NPRM, but that the extreme tip-back condition results in a steeper sliding angle than the original design intent. Boeing requests that we instead specify, among other suggested wording, that “In the extreme tip-back condition, the forward and mid-cabin exits on one side of the airplane could result in steeper sliding angles. * * *”

We partially agree with the requested changes. We disagree with using the words “one side of the airplane” because they imply that passengers and crewmembers could safely evacuate from the side of the airplane with the lower sliding angles. Damage associated with a landing gear failure on the lower side of the airplane could cause passengers and crewmembers to perceive that only the side of the airplane with the sliding angle that is “too steep for evacuation” would be available for emergency evacuation. In addition, this type of failure could render the exits on the lower, damaged side to be unusable and/or unsafe. We agree with the other requested changes because they clarify the unsafe condition. We have revised the Summary section accordingly. However, we have not revised the Discussion section since that section of the preamble does not reappear in the same form in the supplemental NPRM. Instead, the Discussion section in the supplemental NPRM restates the wording of the original NPRM for reference.

Requests To Revise Cost Impact Section

Goodrich Aircraft Interior Products, All Nippon Airways (ANA), Boeing, and Air Transport Association (ATA), on behalf of its member American Airlines, all request that we revise the Cost Impact section of the NPRM. All commenters state that the costs shown in the NPRM are incomplete and should be revised.

We agree with the commenters. The Cost Impact section of the NPRM did not include the cost of the slide-rafts. We have revised the Cost Impact section of the supplemental NPRM to include those costs.

Requests To Extend Compliance Time

Boeing, ANA, and Air New Zealand request that we extend the compliance time. The commenters suggest extending the compliance time from the proposed 5 years to between 8 and 15 years. The commenters make their requests to extend the compliance time for numerous reasons, including:

• The proposed rule has a high economic impact on the operators, with small benefit to safety. Data are missing from the Cost Impact section of the proposed rule.
• The established replacement program (useful service life) of the life-limited slides and slide rafts is 15 years.
• There have been no reports of airplanes tipping back beyond the certified sill height.
• The exit slides and slide-rafts on the opposite side of the airplane would remain within the certified sill heights and corresponding sliding angles due to the roll of the airplane associated with the extreme tip-back condition. The existing slides are not too short to reach the ground (as stated in the proposed rule).
• The slide and slide-raft manufacturer will likely have trouble producing the number of slides and slide-raft units necessary to modify every affected airplane in the worldwide fleet.
• We need to take into consideration low-cycle, high-hour operations.

We partially agree with the commenters' statements. Given the combination of an updated Cost Impact estimate for this supplemental NPRM (see “Request To Revise Cost Impact Section” above), and the risk of exposure to the situation addressed in this supplemental NPRM, we acknowledge that there is merit in revising the compliance time. It is our intent to allow operators to offset, partially, the costs associated with the supplemental NPRM by integrating the compliance time somewhat with the costs associated with normal slide replacement. Therefore, we have changed paragraph (a) of this supplemental NPRM to propose a compliance time of within 72 months after the effective date of the AD.

We have also considered the other reasons commenters gave for extending the compliance time, as discussed below.

• We have determined that an interval based on the “useful service life” of the slides, which is 15 years, would not address the unsafe condition in a timely manner.
• We do not agree that having no reported incidents of airplanes tipping back beyond the certified sill heights is sufficient justification for extending the proposed compliance time. While the specific condition addressed in this supplemental NPRM has not been encountered in service, we have received reports of similar, but less severe, accidents and incidents that could have been more severe given slightly different conditions.
• We do not agree that the exit slides and slide-rafts on the opposite side of the airplane would remain within the certified sill heights and provide a means of safe exit. The gear failure may be associated with or may have caused other damage that would not only raise the exit heights on the far side of the airplane, but also could render the exits on the near side of the airplane unsafe and/or unusable.
• The slide manufacturer has indicated that it is prepared to support operators with sufficient supplies of replacement slides and slide-rafts for the worldwide fleet within the compliance time specified in this supplemental NPRM.

Therefore, although we have extended the compliance time for other reasons, we do not agree that these comments give adequate justification for extending the compliance time any further.

Requests To Withdraw Proposed Rule

ANA, and ATA on behalf of its member American Airlines, suggest that we withdraw the proposed rule because it represents a significant cost and addresses a scenario that is a remote possibility and, therefore, should not be considered an unsafe condition.

American Airlines explains that, with one main landing gear out, the engine would remain attached at “very low speeds” that are associated with taxiing, and would not shear off due to the weight of the airplane, as explained in the “Discussion” section of the proposed rule. American Airlines also explains that the extreme tip-back condition would occur only at extreme aft center-of-gravity (CG) conditions and that there is a low probability of this scenario resulting in a “time limited” (90-second) evacuation. American Airlines further states that there is a low probability of encountering the extreme tip-back position, based on no such occurrences having been encountered over the course of the fleet's high number of flight cycles.

We do not agree with the commenters' requests to withdraw the original NPRM. We consider this to be an unsafe condition for the reasons already given in the original NPRM and for the following reasons.

While we have received information from the airplane manufacturer that indicates that engines could not necessarily shear off the airplane at speeds experienced during taxi, takeoff, landing, or even under some emergency landing situations, further information from the manufacturer indicates that the CG associated with this condition is well within the current accepted operating parameters and is not an extreme condition. However, operators may consider CG restrictions and may make proposals for alternative methods of compliance (AMOC) consideration under the provisions of paragraph (d) of the supplemental NPRM. We will consider requests for approval of an AMOC if sufficient data are submitted to substantiate that the proposal would provide an acceptable level of safety.

In addition, although the specific conditions addressed in the proposed rule have not been encountered in service, we have received reports of partial tip-back during accidents/incidents that could have resulted in extreme tip-back given slightly different conditions, making this type of event foreseeable. During at least one of these partial tip-back events, the slides were deployed to facilitate evacuation. We do not agree that the low probability of encountering such a foreseeable event is justification to withdraw the original NPRM.

Request To Limit the Applicability of the Original NPRM

UPS and ABX Air request that we revise the applicability of the original NPRM. UPS requests that we remove certain Model 767-300F series airplanes from the applicability of the proposed rule because they have a different egress system. ABX Air requests that the applicability of the proposed rule be limited to those airplanes that are required to be equipped with the affected escape slides. For example, the Model 767-300F (freighter) and Model 767-200 or 767-300 series airplanes that have been modified from a passenger configuration to a cargo configuration are not subject to the unsafe condition addressed by the proposed rule.

We agree that airplanes that are not required to be equipped with slides and slide-rafts are not subject to this unsafe condition. The applicability statement of the original NPRM currently includes only Model 767-200 and 767-300 series airplanes and does not include Model 767-300F series airplanes; therefore, no change to the supplemental NPRM is necessary to exclude these airplanes from the applicability. However, we have revised the applicability statement of the supplemental NPRM to state that only Boeing Model 767-200 and -300 series airplanes that are equipped with door-mounted escape slide systems are affected.

Request To Remove Paragraph (b) of the Original NPRM

ABX Air recommends that we remove paragraph (b) of the original NPRM because the second sentence in the proposed rule, “Compliance: Required as indicated, unless accomplished previously,” already gives operators credit for accomplishing the actions before the effective date of the AD.

We agree with the request to remove paragraph (b) of the original NPRM. Paragraph (b) was intended to give operators credit for accomplishing actions in accordance with an earlier version of the referenced service bulletin. However, in this case, there is no earlier version of the service bulletin, and paragraph (b) was included inadvertently in the original NPRM. We have revised the supplemental NPRM accordingly.

Removal of Table 1 of the Original NPRM

We have removed Table 1 of the original NPRM. That table contains information about specific replacement procedures in Boeing Alert Service Bulletin 767-25-0266 that are necessary for each airplane group. We find that information is readily available in any revision of the service bulletin and therefore not necessary to include in the supplemental NPRM.

Conclusion

Certain changes described above expand the scope of the original NPRM. As a result, we have determined that it is necessary to reopen the comment period to provide additional opportunity for the public to comment on this supplemental NPRM.

Cost Impact

There are approximately 745 airplanes of the affected design in the worldwide fleet. The FAA estimates that 261 airplanes of U.S. registry would be affected by this supplemental NPRM. The work hours and required parts per airplane vary according to the configuration group to which the affected airplane belongs. The average labor rate is $80 per work hour. The “Cost Impact Per Airplane Configuration Group” table shows the estimated costs.

Cost Impact per Airplane Configuration Group

Airplane configuration group	U.S.-registered airplanes	Work hours	Kit cost	Slide cost	Cost per airplane	Fleet cost, by configuration group
1	208	6	$1,236	$174,400	$176,116	$36,632,128
2	12	12	2,472	354,264	357,696	4,292,352
3	41	11	98,858	174,400	274,138	11,239,658
4	0	11	34,012	174,400	209,292	0
5	0	17	35,248	354,264	390,872	0

Based on the figures in the “Cost Impact Per Airplane Configuration Group” table, the cost impact of this supplemental NPRM on U.S. operators is estimated to be $52,164,138.

The cost impact figures discussed above are 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 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.

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 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 adding the following new airworthiness directive:

Boeing: Docket 2001-NM-237-AD.

Applicability: Model 767-200 and -300 series airplanes, line numbers 1 through 793 inclusive, certificated in any category; equipped with door-mounted escape slide systems.

Compliance: Required as indicated, unless accomplished previously.

To prevent the escape slides and slide-rafts of the forward and mid-cabin entry and service doors from being too steep for evacuation in the event that the airplane rotates onto the aft fuselage into the extreme tip-back condition, accomplish the following:

Replacement of Slide-Rafts

(a) Within 72 months after the effective date of this AD, replace the applicable slide-rafts at the applicable door or doors, and do all other applicable actions including, but not limited to, changing the latches, and replacing or modifying the counterbalance assemblies, by accomplishing all applicable actions specified in the Accomplishment Instructions in Boeing Service Bulletin 767-25A0266, Revision 2, dated September 27, 2007.

Modification of the Firing Cable

(b) Within 72 months after the effective date of this AD, do a general visual inspection of the slide-raft(s) to determine if supplier part number (P/N) 5A3294-1, 5A3294-2, 5A3295-1, or 5A3295-3 is installed (Boeing P/N S416T214-3, S416T214-4, S416T214-2, and S416T214-1, respectively). Do the inspection in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 767-25A0395, Revision 1, dated January 25, 2007. A review of airplane maintenance records is acceptable in lieu of this inspection if the P/N of the slide-raft can be conclusively determined from that review.

(1) If no affected P/N is installed, no further action is required by this paragraph.

(2) If any affected P/N is installed, before further flight, lengthen the firing cable and test the valve of the inflation trigger system of the escape slide-raft in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 767-25A0395, Revision 1, dated January 25, 2007.

Note 1:

Boeing Alert Service Bulletin 767-25A0395, Revision 1, refers to Goodrich Service Bulletin 5A3294/5A3295-25-362, dated July 25, 2006, as an additional source of service information for lengthening the firing cable and testing the valve of the inflation trigger system of the escape slide-raft.

Credit for Actions Accomplished Previously

(c) Actions done before the effective date of this AD in accordance with the service bulletins listed in Table 1 of this AD are acceptable for compliance with the corresponding requirements of this AD.

Table 1.—Previous Revisions of Service Bulletins

Boeing Alert Service Bulletin	Revision level	Date
767-25A0266	1	December 4, 2006.
767-25A0395	Original	August 31, 2006.

Alternative Methods of Compliance

(d)(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.

Issued in Renton, Washington, on June 5, 2008.

Michael J. Kaszycki,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.