[Federal Register Volume 65, Number 74 (Monday, April 17, 2000)]
[Proposed Rules]
[Pages 20390-20395]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-9557]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-49-AD]
RIN 2120-AA64


Airworthiness Directives; McDonnell Douglas Model DC-8 Series 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to certain McDonnell Douglas Model 
DC-8 series airplanes that have been converted from a passenger to a 
cargo-carrying (``freighter'') configuration. This proposal would 
require a revision to the Airplane Flight Manual Supplement to ensure 
that the main deck cargo door is closed, latched, and locked; 
inspection of the door wire bundle to detect discrepancies and repair 
or replacement of discrepant parts. This proposal also would require, 
among other actions, modification of the hydraulic and indication 
systems of the main deck cargo door, and installation of a means to 
prevent pressurization to an unsafe level if the main deck cargo door 
is not closed, latched, and locked. This proposal is prompted by the 
FAA's determination that certain main deck

[[Page 20391]]

cargo door systems do not provide an adequate level of safety, and that 
there is no means to prevent pressurization to an unsafe level if the 
main deck cargo door is not closed, latched, and locked. The actions 
specified by the proposed AD are intended to prevent opening of the 
cargo door while the airplane is in flight, and consequent rapid 
decompression of the airplane including possible loss of flight control 
or severe structural damage.

DATES: Comments must be received by June 1, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2000-NM-49-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.

FOR FURTHER INFORMATION CONTACT: Michael E. O'Neil, Aerospace Engineer, 
Airframe Branch, ANM-120L, FAA, Transport Airplane Directorate, Los 
Angeles Aircraft Certification Office, 3960 Paramount Boulevard, 
Lakewood, California 90712-4137; telephone (562) 627-5320; fax (562) 
627-5210.

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 2000-NM-49-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. 2000-NM-49-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    Supplemental Type Certificates (STC) SA1063SO and SA1377SO 
[originally issued to Aeronautical Engineers, Inc. (AEI)] specify a 
design for installation of a main deck cargo door, associated door 
cutout in the fuselage, door hydraulic and indication systems, and 
Class ``E'' cargo interior with a cargo barrier on McDonnell Douglas 
Model DC-8 series airplanes. STC SA1063SO installs the main deck cargo 
door and associated hydraulic and indication systems. STC SA1377SO 
installs the Class ``E'' interior with a cargo barrier, a cargo 
handling system, and a 9g crash barrier. The FAA has conducted a design 
review of Model DC-8 series airplanes modified in accordance with STC's 
SA1063SO and SA1377SO and has conducted discussions regarding the 
design with the STC holder. From the design review and these 
discussions, the FAA has identified several potential unsafe 
conditions. [Results of this design review are contained in ``DC-8 
Cargo Modification Review Team, Review of AEI Supplemental Type 
Certificates SA1063SO--Installation of a Cargo Door and SA1377SO--
Installation of a Cargo Interior, Final Report, dated July 30, 1999,'' 
hereinafter referred to as ``the Design Review Report,'' which is 
included in the Rules Docket for this NPRM.]
    For airplanes modified in accordance with STC SA1063SO, this NPRM 
proposes corrective actions for those potential unsafe conditions that 
relate to the hydraulic and indication systems of the main deck cargo 
door and a means to prevent pressurization to an unsafe level if the 
main deck cargo door is not fully closed, latched, and locked. These 
conditions, if not corrected, could result in opening of the cargo door 
while the airplane is in flight, and consequent rapid decompression of 
the airplane including possible loss of flight control or severe 
structural damage.

Other Related Rulemaking

    The FAA is considering further rulemaking to address the remaining 
potential unsafe conditions on Model DC-8 series airplanes modified in 
accordance with STC SA1063SO that relate to the main deck cargo door 
hinge and fuselage structure in the area modified by installation of a 
main deck cargo door. In addition, the FAA is considering further 
rulemaking to address the potential unsafe conditions on Model DC-8 
series airplanes modified in accordance with STC SA1377SO that relate 
to the unreinforced main deck floor, 9g crash barrier, and fire/smoke 
detection system.

Main Deck Cargo Door Systems

    In early 1989, two transport airplane accidents were attributed to 
cargo doors coming open during flight. The first accident involved a 
Boeing Model 747 series airplane in which the cargo door separated from 
the airplane, and damaged the fuselage structure, engines, and 
passenger cabin. The second accident involved a McDonnell Douglas DC-9 
series airplane in which the cargo door opened but did not separate 
from its hinge. The open door disturbed the airflow over the empennage, 
which resulted in loss of flight control and consequent loss of the 
airplane. Although cargo doors have opened occasionally without mishap 
shortly after the airplane was in flight, these two accidents served to 
highlight the extreme potential dangers associated with the opening of 
a cargo door while the airplane is in flight.
    As a result of these cargo door opening accidents, the Air 
Transport Association (ATA) of America formed a task force, including 
representatives of the FAA, to review the design, manufacture, 
maintenance, and operation of airplanes fitted with outward opening 
cargo doors, and to make recommendations to prevent inadvertent cargo 
door openings while the airplane is in flight. A design working group 
was tasked with reviewing 14 CFR part 25.783 [and its accompanying 
Advisory Circular (AC) 25.783-1, dated December 10, 1986] with the 
intent of clarifying its contents and recommending revisions to enhance 
future cargo door designs. This design group also was tasked with 
providing specific recommendations regarding design criteria to be 
applied to existing outward opening cargo doors to ensure that 
inadvertent openings would not occur in the current transport category 
fleet of airplanes.
    The ATA task force made its recommendations in the ``ATA Cargo Door 
Task Force Final Report,'' dated May 15, 1991 (hereinafter referred to 
as ``the ATA Final Report''). On March 20, 1992, the FAA issued a 
memorandum to the managers of the Transport Airplane Directorate (TAD) 
and Los Angeles,

[[Page 20392]]

Seattle, and Atlanta Aircraft Certification Offices (hereinafter 
referred to as ``the FAA Memorandum''), acknowledging ATA's 
recommendations and providing additional guidance for purposes of 
assessing the continuing airworthiness of existing designs of outward 
opening doors. The FAA Memorandum was not intended to upgrade the 
certification basis of the various airplanes, but rather to identify 
criteria to evaluate potential unsafe conditions identified on in-
service airplanes. Appendix 1 of this AD contains the specific 
paragraphs from the FAA Memorandum that set forth the criteria to which 
the outward opening doors should be shown to comply.
    Utilizing the applicable requirements of Civil Air Regulations 
(CAR) part 4b and the design criteria provided by the FAA Memorandum, 
the FAA has reviewed the original type design of major transport 
airplanes, including McDonnell Douglas Model DC-8 airplanes equipped 
with outward opening doors, for any design deficiency or service 
difficulty. Based on that review, the FAA identified unsafe conditions 
and issued, among others, the following AD's and NPRM:
     For certain McDonnell Douglas Model DC-9 series airplanes: 
AD 89-11-02, amendment 39-6216 (54 FR 21416, May 18, 1989);
     For all Boeing Model 747 series airplanes: AD 90-09-06, 
amendment 39-6581 (55 FR 15217, April 23, 1990);
     For certain McDonnell Douglas Model DC-8 series airplanes: 
AD 89-17-01 R1, amendment 39-6521 (55 FR 8446, March 8, 1990);
     For certain Boeing Model 747-100 and -200 series 
airplanes: AD 96-01-51, amendment 39-9492 (61 FR 1703, January 23, 
1996);
     For certain Boeing Model 727-100 and -200 series 
airplanes: AD 96-16-08, amendment 39-9708 (61 FR 41733, August 12, 
1996);
     For certain McDonnell Douglas Model DC-8 series airplanes: 
NPRM Rules Docket No. 99-NM-338-AD (64 FR 72689, December 22, 1999); 
and
     For certain McDonnell Douglas Model DC-8 series airplanes: 
NPRM Rules Docket No. 2000-NM-01-AD (65 FR 7796, February 16, 2000).
    In late 1997, the FAA informed the STC holders and operators of 
Model DC-8 series airplanes that it was embarking on a review of Model 
DC-8 series airplanes that have been converted from a passenger to a 
cargo-carrying (``freighter'') configuration by STC. The FAA proposed 
at a subsequent industry sponsored meeting in early 1998, that DC-8 
operators and STC holders work together to identify and address 
potential safety concerns. This suggestion to the affected industry 
resulted in the creation of the DC-8 Cargo Conversion Joint Task Force 
(JTF) (hereinafter referred to as ``the JTF'').
    The current composition of the JTF includes holders of each of the 
six STC's that addresses the installation of a main deck cargo door in 
Model DC-8 series airplanes and operators and lessors of those modified 
airplanes. At the JTF's request, the FAA participates in its meetings 
to offer counsel and guidance with respect to the FAA's regulatory 
processes. The JTF is a clearinghouse for the gathering and sharing of 
information among the parties affected by the FAA review of STC cargo 
conversions of Model DC-8 series airplanes. The JTF also is a liaison 
between the FAA, operators, and STC holders.
    The JTF has been working with the FAA to provide data relating to 
the number of STC modified Model DC-8 series airplanes and operators of 
those airplanes, and identified which airplanes are modified by each 
STC. It also was instrumental in polling the operators and providing 
maintenance schedules and locations to the FAA, which helped the FAA 
arrange visits to operators of airplanes modified by each of the STC's. 
These visits allowed the FAA to review both the available data 
supporting each STC and modified airplanes and to identify potential 
safety concerns with each of the STC modifications. Additionally, the 
JTF has coordinated funding of the industry review of the data 
supporting the STC's and ongoing efforts to resolve safety issues 
identified by the FAA.
    Using the applicable requirements of CAR part 4b and the criteria 
specified in the FAA Memorandum as evaluation guides, the FAA, in 
collaboration with the JTF, conducted an engineering design review and 
inspection of an airplane modified in accordance with STC SA1063SO. The 
FAA identified a number of design features of the main deck cargo door 
systems of STC SA1063SO that are unsafe and do not meet the applicable 
requirements of CAR part 4b or the criteria specified in the FAA 
Memorandum. These systems include the door indication and hydraulic 
systems. The FAA design review team also determined that the design 
data of this STC did not include an adequate safety analysis of the 
main deck cargo door systems.
    For airplanes modified in accordance with STC SA1063SO, the FAA 
considers the following five specific design deficiencies of the main 
deck cargo door systems to be unsafe:

1. Indication System

    The main deck cargo door indication system for STC SA1063SO 
utilizes door warning lights at the door operator's control panel and 
the flight engineer's panel. The warning lights do not indicate either 
the door open or closed status, or latch or lock status. All three 
conditions (i.e., door closed, latched, and locked) must be monitored 
directly so that the door indication system cannot display either 
``latched'' before the door is closed or ``locked'' before the door is 
latched. If a sequencing error caused the door to latch and lock 
without being fully closed, the subject indication system, as currently 
designed, would not alert the door operator or the flight engineer of 
this condition. As a result, the airplane could be dispatched with the 
main deck cargo door unsecured, which could lead to the cargo door 
opening while the airplane is in flight.
    The light on the flight engineer's panel is labeled ``Cargo Door'' 
and is displayed in red since it indicates an event that requires 
immediate pilot action. However, if the flight engineer is temporarily 
away from his station, a door unsafe warning indication could be missed 
by the pilots. In addition, the flight engineer could miss such an 
indication by not scanning the panel. As a result, the pilots and 
flight engineer could be unaware of or misinterpret an unsafe condition 
and could fail to respond in the correct manner. The warning lights 
have a ``Press-to-Test'' feature which is adequate to check the light 
bulb functionality, but is not adequate to check the cargo door closed, 
latched, and locked functions. Therefore, an indicator light that 
monitors all three conditions (i.e., door closed, latched, and locked) 
must be located in front of and in plain view of both pilots since one 
of the pilot's stations is always occupied during flight operations.
    During an FAA review of STC modified airplanes, instances of 
distress of the wire bundle between the fuselage and main deck cargo 
door and the associated attach hardware were noted. Therefore, a one-
time general visual inspection of this area to detect crimped, frayed, 
or chafed wires is necessary to ensure the electrical continuity of the 
existing door indication system during the interim period.

2. Means to Visually Inspect the Locking Mechanism

    The locking system of STC SA1063SO consists of a lock pin installed 
at one of the seven latches of the main deck cargo

[[Page 20393]]

door. The single view port of the main deck cargo door installed in 
accordance with STC SA1063SO monitors the position of the torque tube 
that actuates the door latches, but does not provide a means to ensure 
the position of the lock pin. Therefore, a means to visually inspect 
the door locking mechanism must be installed to ensure that the door is 
fully closed, latched, and locked.
    As discussed in the ATA Final Report and the FAA Memorandum, there 
should be a means of directly inspecting each lock or, at a minimum, 
the locks at each end of the lock shaft of certain designs, such that a 
failure condition in the lock shaft would be detectable.

3. Means to Prevent Pressurization to an Unsafe Level

    McDonnell Douglas Model DC-8 series airplanes modified in 
accordance with STC SA1063SO are not equipped with a means to prevent 
pressurization of the airplane to an unsafe level in the event that the 
main deck cargo door is not fully closed, latched, and locked. 
Therefore, such a means must be installed.

4. Powered Lock Systems

    STC SA1063SO utilizes a nose gear squat switch to remove power 
(i.e., electrical and hydraulic) from the door control master switch 
while the airplane is in flight. Latent failure of the squat switch 
together with other latent and/or single point failures could 
precipitate inadvertent door openings. Therefore, a means to remove 
power from the door controls must be installed to prevent inadvertent 
opening of the main deck cargo door in flight.
    A systems safety analysis would normally evaluate and resolve the 
potential for these types of unsafe conditions. The need for a system 
safety analysis is identified in the ATA Final Report and the FAA 
Memorandum.

5. Lock Strength

    Analysis of the existing latching and locking mechanism of the main 
deck cargo door indicates that in the event of a system jam, continued 
operation of the hydraulic cylinders could result in structural 
deformation of elements of the latching and locking mechanisms. 
Structural deformation of the locking mechanism could result in the 
single door latch equipped with a lock not being locked and consequent 
erroneous indication to the pilots that the latch is locked properly. 
Further, the FAA has determined that a lock on a single latch is 
inadequate to provide the level of safety envisioned by the applicable 
certification requirements. Therefore, the latching and locking systems 
for the main deck cargo door must be modified to prevent structural 
deformation, which could result in incorrect indication to the pilots 
that the door is not fully closed, latched, and locked.

Explanation of Requirements of Proposed Rule

    Since unsafe conditions have been identified that are likely to 
exist or develop on other products of this same type design, the 
proposed AD would require, within 60 days after the effective date of 
this AD, a general visual inspection of the wire bundle of the main 
deck cargo door between the exit point of the cargo liner and the 
attachment point on the main deck cargo door to detect crimped, frayed, 
or chafed wires; a general visual inspection for damaged, loose, or 
missing hardware mounting components; and repair, if necessary. These 
actions would be required to be accomplished in accordance with FAA-
approved maintenance procedures.
    The proposed AD also would require, within 60 days after the 
effective date of the AD, a revision of the Limitations Section of the 
appropriate FAA-approved Airplane Flight Manual Supplement (AFMS) for 
STC SA1063SO by inserting therein procedures to ensure that the main 
deck cargo door is closed, latched, and locked prior to dispatch of the 
airplane; and installation of any associated placards. These actions 
would be required to be accomplished in accordance with a method 
approved by the Manager, Los Angeles Aircraft Certification Office 
(ACO), FAA, Transport Airplane Directorate.
    The proposed AD also would require, within 18 months after the 
effective date of this AD, the following actions:
     Modification of the indication system of the main deck 
cargo door to indicate to the pilots whether the main deck cargo door 
is fully closed, latched, and locked;
     Modification of the mechanical and hydraulic systems of 
the main deck cargo door to eliminate detrimental deformation of the 
elements of the door latching and locking mechanisms;
     Installation of a means to visually inspect the locking 
mechanism of the main deck cargo door;
     Installation of a means to remove power to the door while 
the airplane is in flight; and
     Installation of a means to prevent pressurization to an 
unsafe level if the main deck cargo door is not fully closed, latched, 
and locked.
    The modifications and installations would be required to be 
accomplished in accordance with a method approved by the Manager, Los 
Angeles ACO. Accomplishment of the modifications and installations 
would constitute terminating action for the inspections, AFMS revision, 
and associated placards described previously.

Cost Impact

    There are approximately 15 Model DC-8 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 11 
airplanes of U.S. registry would be affected by this proposed AD.
    It would take approximately 1 work hour per airplane to accomplish 
the general visual inspections, at an average labor rate of $60 per 
work hour. Based on these figures, the cost impact of the general 
visual inspections proposed by this AD on U.S. operators is estimated 
to be $660, or $60 per airplane, per inspection cycle.
    It would take approximately 1 work hour per airplane to accomplish 
the AFMS revision and installation of associated placards, at an 
average labor rate of $60 per work hour. Based on these figures, the 
cost impact of the AFMS revision and installation of associated 
placards proposed by this AD on U.S. operators is estimated to be $660, 
or $60 per airplane.
    The FAA estimates that it would take approximately 210 work hours 
per airplane to accomplish the modification required by paragraph (c) 
of the proposed AD, at an average labor rate of $60 per work hour. The 
FAA also estimates that required parts would cost approximately $45,000 
per airplane. Based on these figures, the cost impact of this 
modification proposed by this AD on U.S. operators is estimated to be 
$633,600, or $57,600 per airplane.
    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.

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

[[Page 20394]]

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.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

McDonnell Douglas: Docket 2000-NM-49-AD.

    Applicability: Model DC-8 series airplanes that have been 
converted from a passenger to a cargo-carrying (``freighter'') 
configuration in accordance with Supplemental Type Certificate (STC) 
SA1063SO; 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 (e) 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 opening of the cargo door while the airplane is in 
flight, and consequent rapid decompression of the airplane including 
possible loss of flight control or severe structural damage, 
accomplish the following:

Actions Addressing the Main Deck Cargo Door

    (a) Within 60 days after the effective date of this AD, 
accomplish a general visual inspection of the wire bundle of the 
main deck cargo door between the exit point of the cargo liner and 
the attachment point on the main deck cargo door to detect crimped, 
frayed, or chafed wires; and perform a general visual inspection for 
damaged, loose, or missing hardware mounting components. If any 
crimped, frayed, or chafed wire, or damaged, loose, or missing 
hardware mounting component is detected, prior to further flight, 
repair in accordance with FAA-approved maintenance procedures.

    Note 2: For the purposes of this AD, a general visual inspection 
is defined as ``A visual examination of an interior or exterior 
area, installation, or assembly to detect obvious damage, failure, 
or irregularity. This level of inspection is made under normally 
available lighting conditions such as daylight, hangar lighting, 
flashlight, or drop-light, and may require removal or opening of 
access panels or doors. Stands, ladders, or platforms may be 
required to gain proximity to the area being checked.''

    (b) Within 60 days after the effective date of this AD, revise 
the Limitations Section of the appropriate FAA-approved Airplane 
Flight Manual Supplement (AFMS) for STC SA1063SO by inserting 
therein procedures to ensure that the main deck cargo door is fully 
closed, latched, and locked prior to dispatch of the airplane, and 
install any associated placards. The AFMS revision procedures and 
installation of any associated placards shall be accomplished in 
accordance with a method approved by the Manager, Los Angeles 
Aircraft Certification Office (ACO), FAA, Transport Airplane 
Directorate.

Actions Addressing the Main Deck Cargo Door Systems

    (c) Within 18 months after the effective date of this AD, 
accomplish the actions specified in paragraphs (c)(1), (c)(2), 
(c)(3), (c)(4), and (c)(5) of this AD in accordance with a method 
approved by the Manager, Los Angeles ACO.
    (1) Modify the indication system of the main deck cargo door to 
indicate to the pilots whether the main deck cargo door is fully 
closed, latched, and locked;
    (2) Modify the mechanical and hydraulic systems of the main deck 
cargo door to eliminate detrimental deformation of elements of the 
door latching and locking mechanism;
    (3) Install a means to visually inspect the locking mechanism of 
the main deck cargo door;
    (4) Install a means to remove power to the door while the 
airplane is in flight;
    (5) Install a means to prevent pressurization to an unsafe level 
if the main deck cargo door is not fully closed, latched, and 
locked.
    (d) Compliance with paragraphs (c)(1), (c)(2), (c)(3), (c)(4), 
and (c)(5) of this AD constitutes terminating action for the 
requirements of paragraphs (a) and (b) of this AD, and the AFMS 
revision and placards may be removed.

Alternative Methods of Compliance

    (e) 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, Los Angeles ACO. Operators shall 
submit their requests through an appropriate FAA Principal 
Maintenance Inspector, who may add comments and then send it to the 
Manager, Los Angeles ACO.

    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Los Angeles ACO.

Special Flight Permit

    (f) 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.

Appendix 1

Excerpt from an FAA Memorandum to Director-Airworthiness and Technical 
Standards of ATA, dated March 20, 1992

    ``(1) Indication System:
    (a) The indication system must monitor the closed, latched, and 
locked positions, directly.
    (b) The indicator should be amber unless it concerns an outward 
opening door whose opening during takeoff could present an immediate 
hazard to the airplane. In that case the indicator must be red and 
located in plain view in front of the pilots. An aural warning is 
also advisable. A display on the master caution/warning system is 
also acceptable as an indicator. For the purpose of complying with 
this paragraph, an immediate hazard is defined as significant 
reduction in controllability, structural damage, or impact with 
other structures, engines, or controls.
    (c) Loss of indication or a false indication of a closed, 
latched, and locked condition must be improbable.
    (d) A warning indication must be provided at the door operators 
station that monitors the door latched and locked conditions 
directly, unless the operator has a visual indication that the door 
is fully closed and locked. For example, a vent door that monitors 
the door locks and can be seen from the operators station would meet 
this requirement.
    (2) Means to Visually Inspect the Locking Mechanism:
    There must be a visual means of directly inspecting the locks. 
Where all locks are tied to a common lock shaft, a means of 
inspecting the locks at each end may be sufficient to meet this 
requirement provided no failure condition in the lock shaft would go 
undetected when viewing the end locks. Viewing latches may be used 
as an alternate to viewing locks on some installations where there 
are other compensating features.
    (3) Means to Prevent Pressurization:
    All doors must have provisions to prevent initiation of 
pressurization of the airplane to an unsafe level, if the door is 
not fully closed, latched and locked.
    (4) Lock Strength:

[[Page 20395]]

    Locks must be designed to withstand the maximum output power of 
the actuators and maximum expected manual operating forces treated 
as a limit load. Under these conditions, the door must remain 
closed, latched and locked.
    (5) Power Availability:
    All power to the door must be removed in flight and it must not 
be possible for the flight crew to restore power to the door while 
in flight.
    (6) Powered Lock Systems:
    For doors that have powered lock systems, it must be shown by 
safety analysis that inadvertent opening of the door after it is 
fully closed, latched and locked, is extremely improbable.''

    Issued in Renton, Washington, on April 11, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-9557 Filed 4-14-00; 8:45 am]
BILLING CODE 4910-13-P