Airworthiness Directives; Boeing Model 757 and 767 Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-NM-03-AD]

Airworthiness Directives; Boeing Model 757 and 767 Series

Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: This document proposes the adoption of a new airworthiness

directive (AD) that is applicable to certain Boeing Model 757 and 767

series airplanes. This proposal would require modification of the latch

hook installation for the number two cockpit window frame. This

proposal is prompted by reports of the flight crew executing rejected

takeoffs (RTO) and air turnbacks (ATB) due to false ``closed''

indications for the number two cockpit window. The actions specified by

the proposed AD are intended to prevent unlatched (not completely

closed) number two cockpit windows and the resultant execution of RTO's

and ATB's by the flight crew.

DATES: Comments must be received by May 2, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-103,

Attention: Rules Docket No. 94-NM-03-AD, 1601 Lind Avenue, SW., Renton,

Washington 98055-4056. Comments may be inspected at this location

between 9 a.m. and 3 p.m., Monday through Friday, except Federal

holidays.

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: Roy Boffo, Aerospace Engineer,

Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle

Aircraft Certification Office, 1601 Lind Avenue, SW., Renton,

Washington 98055-4056; telephone (206) 227-2780; fax (206) 227-1181.

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 notice may be changed in

light of the comments received.

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 notice must submit a self-addressed,

stamped postcard on which the following statement is made: ``Comments

to Docket Number 94-NM-03-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-103, Attention: Rules

Docket No. 94-NM-03-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056

Discussion

Recently, the FAA has received several reports from an operator of

Boeing Model 757-200 series airplanes that the flight crew executed

rejected takeoffs (RTO) due to the number two cockpit window failing to

close completely. In two of these incidents, the RTO's were initiated

at 120 knots. As a result, this operator developed special procedures

to ensure that these windows were latched prior to each flight.

However, these procedures proved to be ineffective, as evidenced by the

subsequent execution of four additional RTO's.

Further, several operators of Boeing Model 767 series airplanes

recently reported that the flight crew executed air turnbacks (ATB) due

to false ``closed'' indications for the number two cockpit window.

Although the latch indicator showed ``closed,'' the number two cockpit

window was not completely latched, which resulted in noise in the

cockpit.

Investigation into the cause of these unlatched windows revealed

that, although the latch handle, which operates a flexible cable that

moves four latch cams on the upper, lower, and aft edges of the window

frame, may be moved to the ``latched'' (closed) position, the latch

cams may not fully engage the latch posts.

The latch handles must be in the ``unlatched'' (opened) position to

permit the window to travel to the fully closed position. By rotating

the latch handle 180 degrees to the ``latched'' position, the latch

cams on the window frame should engage the latch stud on the body of

the window frame to prevent the window from opening and to lock the

window closed. If the windows do not close completely, cabin

pressurization and speed limits will be adversely affected during RTO's

and ATB's.

This condition, if not corrected, could result in the flight crew

executing RTO's and ATB's due to unlatched (not completely closed)

number two cockpit windows.

The FAA has reviewed and approved Boeing Service Bulletin 757-56-

0007, dated May 6, 1993 (for Model 757 series airplanes), and Boeing

Service Bulletin 767-56-002, dated August 30, 1985, as amended by

Notice of Status Change (NSC) Number 767-56-0002 NSC 1, dated July 3,

1986 (for Model 767 series airplanes), that describe procedures for

modification of the latch hook installation for the number two cockpit

window frame. This modification entails adding a cam latch hook to the

window frame; removing a bolt and nut from the window post; and

installing a bolt, spacer, and nut on the window post to strike and

move the latch hook away from the latch cam when the window is closed.

(The number two cockpit window on the Model 757 and 767 series

airplanes are similar in design.)

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 require modification of the latch hook installation

for the number two cockpit window frame. The actions would be required

to be accomplished in accordance with the applicable service bulletin

and NSC described previously.

There are approximately 640 Model 757 and 767 series airplanes of

the affected design in the worldwide fleet. The FAA estimates that 409

airplanes of U.S. registry would be affected by this proposed AD, that

it would take approximately 8 work hours per airplane to accomplish the

proposed actions, and that the average labor rate is $55 per work hour.

Required parts would cost approximately $2,000 per airplane. Based on

these figures, the total cost impact of the proposed AD on U.S.

operators is estimated to be $997,960, or $2,440 per airplane.

The total 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 AD were not adopted.

The regulations proposed herein would not have substantial direct

effects 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, in

accordance with Executive Order 12612, it is determined that this

proposal would not have sufficient federalism implications to warrant

the preparation of a Federalism Assessment.

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 14

CFR part 39 of the Federal Aviation Regulations as follows:

PART 39--AIRWORTHINESS DIRECTIVES

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

Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C.

106(g); and 14 CFR 11.89.

39.13 [Amended]

2. Section 39.13 is amended by adding the following new

airworthiness directive:

Boeing: Docket 94-NM-03-AD.

Applicability: Model 757 series airplanes having line positions

1 through 534 inclusive, and Model 767 series airplanes having line

positions 1 through 114 inclusive; certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent unlatched (not completely closed) number two cockpit

windows and the resultant execution of rejected takeoffs and air

turnbacks by the flight crew, accomplish the following: (a) Within

18 months after the effective date of this AD, modify the latch hook

installation for the number two cockpit window frame in accordance

with Boeing Service Bulletin 757-56-0007, dated May 6, 1993 (for

Model 757 series airplanes); or Boeing Service Bulletin 767-56-0002,

dated August 30, 1985, as amended by Notice of Status Change Number

767-56-0002 NSC 1, dated July 3, 1986 (for Model 767 series

airplanes); as applicable.

(b) 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 Aircraft Certification

Office (ACO), FAA, Transport Airplane Directorate. 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: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the Seattle ACO.

(c) Special flight permits may be issued in accordance with

Federal Aviation Regulations (FAR) 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 March 2, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-5241 Filed 03-07-94; 8:45 am]

BILLING CODE 4910-13-U