Federal Register / Vol. 62, No. 62 / Tuesday, April 1, 1997 / Proposed Rules 15433

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 (b) 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 uncommanded activation of the

rudder trim, which, if not corrected, could

lead to uncommanded yaw/roll excursions

and consequent reduced controllability of the

airplane, accomplish the following:

(a) Within 90 days after the effective date

of this AD, replace the rudder trim switch,

control knob, and associated wires with new

components and wiring in accordance with

the applicable Airbus Industrie service

bulletin specified in paragraph (a)(1) or (a)(2)

of this AD.

(1) For Model A300–600 series airplanes:

Airbus Service Bulletins A300–27–6022,

Revision 2, dated August 28, 1995; and

A300–27–6027, Revision 2, dated August 22,

1995, or Revision 3, dated March 13, 1996.

(2) For Model A310 series airplanes:

Airbus Service Bulletins A310–27–2058,

Revision 2, dated August 28, 1995; and

A310–27–2071, Revision 2, dated August 22,

1995, or Revision 3, dated March 13, 1996.

Note 2: Modifications accomplished prior

to the effective date of this AD in accordance

with Airbus Service Bulletin A300–27–6027,

Revision 2, dated August 22, 1995 (for Model

A300–600 series airplanes), or A310–27–

2071, Revision 2, dated August 22, 1995 (for

Model A310 series airplanes), are considered

acceptable for compliance with the

applicable action specified in this AD.

(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,

Standardization Branch, ANM–113, 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, Standardization

Branch, ANM–113.

Note 3: Information concerning the

existence of approved alternative methods of

compliance with this AD, if any, may be

obtained from the Standardization Branch,

ANM–113.

(c) 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 March

25, 1997.

Darrell M. Pederson,

Acting Manager, Transport Airplane

Directorate, Aircraft Certification Service.

[FR Doc. 97–8126 Filed 3–31–97; 8:45 am]

BILLING CODE 4910–13–U

14 CFR Part 39

[Docket No. 96–NM–171–AD]

RIN 2120–AA64

Airworthiness Directives; Boeing

Model 747–400, –400D, and –400F

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 747–400, –400D,

and –400F series airplanes. This

proposal would require modification of

the P212 and P213 panels of the cabin

pressure control system. This proposal

is prompted by a report of in-flight loss

of cabin pressurization control due to a

single failure of the auxiliary power unit

(APU) battery. The actions specified by

the proposed AD are intended to

prevent loss of control of the cabin

pressurization system, which could

result in rapid depressurization of the

airplane. Such rapid depressurization

could result in deleterious physiological

effects on the passengers and crew; and

airplane diversions, which represent an

increased risk to the airplane,

passengers, and crew.

DATES: Comments must be received by

May 9, 1997.

ADDRESSES: Submit comments in

triplicate to the Federal Aviation

Administration (FAA), Transport

Airplane Directorate, ANM–103,

Attention: Rules Docket No. 96–NM–

171–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.

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:

Clayton R. Morris, Jr., Aerospace

Engineer, Systems and Equipment

Branch, ANM–130S, FAA, Seattle

Aircraft Certification Office, 1601 Lind

Avenue, SW., Renton, Washington;

telephone (206) 227–2794; 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 96–NM–171–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.

96–NM–171–AD, 1601 Lind Avenue,

SW., Renton, Washington 98055–4056.

Discussion

The FAA received a report indicating

that power from the 28-volt direct

current (DC) hot battery bus of the

auxiliary power unit (APU) was lost

during flight on a Model 747–400 series

airplane. Loss of power from the hot

battery bus resulted in loss of a discrete

signal to both interface control units

(ICU’s). Loss of the discrete signal

indicated that ‘‘manual’’ control mode

was selected, but the cabin pressure

control system was still in ‘‘automatic’’

control mode. The ICU’s went into

standby mode and transmitted this

status to both cabin pressure controllers

(CPC’s). The CPC’s then went into
15434 Federal Register / Vol. 62, No. 62 / Tuesday, April 1, 1997 / Proposed Rules

standby mode and ceased trying to

control the outflow valves.

Loss of power from the hot battery bus

also prevented the flight crew from

driving the outflow valves in the

‘‘manual’’ control mode. When the

ICU’s went into standby mode, power to

the outflow valve brakes was severed;

this caused the brakes to engage. With

the brakes engaged, the outflow valves

were locked in the last commanded

position. The flight crew reported

receiving several engine indication and

crew alerting system (EICAS) messages,

and followed procedures to select the

cabin pressurization control system to

‘‘manual’’ control mode.

The airplane continued to cruise at an

altitude of 35,000 feet without cabin

pressurization problems. The cabin

pressure differential at 35,000 feet was

about 8.6 pounds per square inch

differential (psid). (Cabin pressure

differential is the difference between the

airplane cabin pressure and the ambient

pressure; 8.6 psid is considered to be

normal at an altitude of 35,000 feet.)

Later during the flight, the flight crew

initiated a step climb to 39,000 feet. The

combination of both outflow valves

being locked in the last commanded

position and the decrease in ambient

pressure [about 0.6 pounds per square

inch (psi)] due to the step climb caused

the cabin pressure differential to

increase to just over 9.1 psid. Both

positive pressure relief valves opened

due to the higher cabin pressure

differential. With the air conditioning

packs operating in ‘‘Hi Flow’’ mode and

the positive pressure relief valves open,

air conditioning pack number 2

automatically was commanded ‘‘OFF.’’

The flight crew also selected one of the

two remaining air conditioning packs

‘‘OFF.’’ The loss of two-thirds of the

cabin air inflow plus both outflow

valves locking in the last commanded

position caused the cabin pressure

altitude to climb rapidly. At some point

within two minutes after initiation of

the step climb, the flight crew should

have received a cabin pressure altitude

warning at 10,000 feet and initiated an

emergency descent. Analysis indicates

that the cabin pressure altitude may

have reached as high as 16,000 feet. The

flight crew leveled off at 14,000 feet and

diverted the airplane.

The flight crew landed the airplane

about 50 minutes later with one air

conditioning pack still operating, which

caused the airplane to repressurize

above the maximum pressure

differential allowed to open the

passenger doors. The flight crew turned

off the last air conditioning pack about

five minutes after landing (at a cabin

pressure differential of about 0.7 psid).

The airplane depressurized within one

minute; the crew then was able to open

the passenger doors.

Unsafe Conditions

Because the flight crew could not

control the cabin pressurization system

during flight, rapid depressurization of

the airplane occurred. Such rapid

depressurization increases the potential

for deleterious physiological effects on

the passengers and crew. In addition,

the inability to control cabin

pressurization can result in airplane

diversions, which represent an

increased risk to the airplane,

passengers, and crew due to the

unplanned nature of the event and the

potential for overweight landings.

Additionally, when the cabin pressure

differential exceeded the maximum

pressure differential allowed to open the

passenger doors after landing, the only

means available to reduce the cabin

pressure differential to a level low

enough to allow the doors to be opened

was through the airplane’s inherent

leakage. If an emergency condition

existed upon landing (e.g., cabin fire,

airplane fire, ditching, etc.) that

required the passengers and crew to

immediately exit the airplane, the crew

would not have been able to open the

passenger doors.

Explanation of Relevant Service

Information

The FAA has reviewed and approved

Boeing Alert Service Bulletin 747–

21A2381, dated June 27, 1996, which

describes procedures for modification of

the P212 and P213 panels of the cabin

pressure control system.

Accomplishment of the modification

entails the following:

• For certain airplane groups:

changing the wiring in the P212 and

P213 panels; replacing the existing twopole relays with new four-pole relays;

and performing a test of both panels.

• For one airplane group,

accomplishment of the modification

involves changing the wiring in the

P212 panel; replacing the existing twopole relays with new four-pole relays;

replacing the existing P213 panel with

a new P213 panel; and performing a test

of both panels.

Accomplishment of the modification

will provide power to the ICU and

continuous auto control of cabin

pressurization when the APU hot

battery bus is lost.

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

require modification of the P212 and

P213 panels of the cabin pressure

control system. The actions would be

required to be accomplished in

accordance with the alert service

bulletin described previously.

Cost Impact

There are approximately 351 Boeing

Model 747–400, –400D, and –400F

series airplanes of the affected design in

the worldwide fleet. The FAA estimates

that 43 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 $60 per work hour. Required parts

would cost approximately $389 per

airplane. Based on these figures, the cost

impact of the proposed AD on U.S.

operators is estimated to be $37,367, or

$869 per airplane.

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 AD were not adopted.

Regulatory Impact

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.
Federal Register / Vol. 62, No. 62 / Tuesday, April 1, 1997 / Proposed Rules 15435

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 96–NM–171–AD.

Applicability: Model 747–400, –400D, and

–400F series airplanes; as identified in

Boeing Alert Service Bulletin 747–21A2381,

dated June 27, 1996, 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 (b) 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 loss of control of the cabin

pressurization system, which could result in

rapid depressurization of the airplane and

consequent deleterious physiological effects

on the passengers and crew; and airplane

diversions, which represent an increased risk

to the airplane, passengers, and crew;

accomplish the following:

(a) Within 180 days after the effective date

of this AD, modify the P212 and P213 panels

of the cabin pressure control system as

specified in paragraph (a)(1) or (a)(2) of this

AD, as applicable, in accordance with Boeing

Alert Service Bulletin 747–21A2381, dated

June 27, 1996.

(1) For Groups 1 through 7 airplanes, as

identified in the alert service bulletin:

Change the wiring in the P212 and P213

panels; replace the existing two-pole relays

with new four-pole relays; and perform a test

of both panels.

(2) For Group 8 airplanes, as identified in

the alert service bulletin: Change the wiring

in the P212 panel; replace the existing twopole relays with new four-pole relays; replace

the existing P213 panel with a new P213

panel; and perform a test of both panels.

(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 2: 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 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 March

25, 1997.

Darrell M. Pederson,

Acting Manager, Transport Airplane

Directorate, Aircraft Certification Service.

[FR Doc. 97–8129 Filed 3–31–97; 8:45 am]

BILLING CODE 4910–13–U

14 CFR Part 39

[Docket No. 97–NM–25–AD]

RIN 2120–AA64

Airworthiness Directives; Boeing

Model 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 767 series

airplanes. This proposal would require

a one-time inspection of the main

landing gear (MLG) retaining bolt to

ensure that it is installed correctly, and

adjustments or repairs, if necessary.

This proposal is prompted by a report

indicating that a disconnected retaining

bolt was found in the MLG forward

trunnion joint of a Model 767 series

airplane. The actions specified by the

proposed AD are intended to prevent

aft-acting trunnion loads from being

transferred to the MLG beam, and

consequent fracture and collapse of the

MLG; this condition could result in the

loss of control of the airplane on the

ground.

DATES: Comments must be received by

May 9, 1997.

ADDRESSES: Submit comments in

triplicate to the Federal Aviation

Administration (FAA), Transport

Airplane Directorate, ANM–103,

Attention: Rules Docket No. 97–NM–

25–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.

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:

James G. Rehrl, Aerospace Engineer,

Airframe Branch, ANM–120S, FAA,

Seattle Aircraft Certification Office,

1601 Lind Avenue, SW., Renton,

Washington; telephone (206) 227–2783;

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 97–NM–25–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.

97–NM–25–AD, 1601 Lind Avenue,

SW., Renton, Washington 98055–4056.