[Federal Register Volume 64, Number 218 (Friday, November 12, 1999)]
[Proposed Rules]
[Pages 61540-61547]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-29475]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 97-NM-234-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 727 Series Airplanes
Modified in Accordance with Supplemental Type Certificate ST00015AT
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 Boeing Model 727 series
airplanes that have been converted from a passenger to a cargo-carrying
(``freighter'') configuration. This proposal would require, among other
actions, installation of a fail-safe hinge, redesigned main deck cargo
door warning and power control systems, and 9g cargo barrier. This
proposal is
[[Page 61541]]
prompted by the FAA's determination that the main deck cargo door hinge
is not fail-safe; that certain main deck cargo door control systems do
not provide an adequate level of safety; and that the main deck cargo
barrier is not structurally adequate during an emergency landing. The
actions specified by the proposed AD are intended to prevent structural
failure of the main deck cargo door hinge or failure of the cargo door
system, which could result in the loss or opening of the cargo door
while the airplane is in flight, rapid decompression, and structural
damage to the airplane; and to prevent failure of the main deck cargo
barrier during an emergency landing, which could injure occupants.
DATES: Comments must be received by December 27. 1999.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-114,
Attention: Rules Docket No. 97-NM-234-AD, 1601 Lind Avenue, SW.,
Renton, Washington 98055-4056. Comments may be inspected at this
location by appointment only between the hours of 9:00 a.m. and 3:00
p.m., Monday through Friday, except Federal holidays.
FOR FURTHER INFORMATION CONTACT: Michael O'Neil, Aerospace Engineer,
Airframe Branch, ANM-120L, FAA, Transport Airplane Directorate, Los
Angeles Aircraft Certification Office, 3960 Paramount Boulevard,
Lakewood, California 90712; 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 97-NM-234-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. 97-NM-234-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
Supplemental Type Certificate (STC) ST00015AT (held by Kitty Hawk
Air Cargo) specifies a design for a main deck cargo door, associated
cargo door cutout, door systems, and Class ``E'' cargo interior with a
cargo barrier. As discussed in notice of proposed rulemaking (NPRM),
Rules Docket No. 97-NM-80-AD [the final rule, AD 98-26-20, amendment
39-10963, was published in the Federal Register on January 12, 1999 (64
FR 2038)], which is applicable to certain Boeing Model 727 series
airplanes that have been converted from a passenger to a cargo-carrying
(``freighter'') configuration, the FAA has conducted a design review of
Boeing Model 727 series airplanes modified in accordance with STC
ST00015AT and has identified several potential unsafe conditions.
[Results of this design review are contained in ``FAA Freighter
Conversion STC Review, Report Number 4, dated February 6, 1997,''
hereinafter referred to as ``the Design Review Report,'' which is
included in the Rules Docket for this NPRM.] This NPRM proposes
corrective action for three of those potential unsafe conditions that
relate to the following three areas: main deck cargo door hinge, main
deck cargo door systems, and main deck cargo barrier.
Main Deck Cargo Door Hinge
In order to avoid catastrophic structural failure, it has been a
typical industry approach to design outward opening cargo doors and
their attaching structure to be fail-safe (i.e., designed so that if a
single structural element fails, other structural elements are able to
carry the redistributed load). Another potential design approach is
safe-life, where the critical structure is shown by analyses and/or
tests to be capable of withstanding the repeated loads of variable
magnitude expected in service for a specific service life. Safe-life is
usually not used on critical structure because it is difficult to
account for manufacturing or in-service accidental damage. For this
reason, plus the fact that none of the STC holders have provided data
in support of this approach, the safe-life approach will not be
discussed further regarding the design and construction of the main
deck cargo door hinge.
Structural elements such as the main deck cargo door hinge are
subject to severe in-service operating conditions that could result in
corrosion, binding, or seizure of the hinge. These conditions, in
addition to the normal operational loads, can lead to early and
unpredictable fatigue cracking. If a main deck cargo door hinge is not
a fail-safe design, a fatigue crack could initiate and propagate
longitudinally undetected, which could lead to a complete hinge
failure. A possible consequence of this undetected failure is the
opening of the main deck cargo door while the airplane is in flight.
Service experience indicates that the opening of a cargo door while the
airplane is in flight can be extremely hazardous in a variety of ways
including possible loss of flight control, severe structural damage, or
rapid decompression, any of which, could lead to loss of the airplane.
The design of the main deck cargo door hinge must be in compliance
with Civil Air Regulations (CAR) part 4b, including CAR part 4b.270,
which requires, in part, that catastrophic failure or excessive
structural deformation, which could adversely affect the flight
characteristics of the airplane, is not probable after fatigue failure
or obvious partial failure of a single principal structural element.
One common feature of a fail-safe hinge design is a division of the
hinge into multiple segments such that, following failure of any one
segment, the remaining segments would support the redistributed load.
The main deck cargo door installed in accordance with STC ST00015AT
is supported by latches along the bottom of the door and a two-segment
hinge along the top. This two-segment hinge is considered a critical
structural element for this STC. A crack that initiates and propagates
longitudinally along either segment of the hinge will eventually result
in failure of the entire hinge, because the remaining segment of the
hinge is unable to support the redistributed loads. Failure of the
entire hinge can result in the opening of the main deck cargo door
while the airplane is in flight.
On other Boeing Model 727 series airplanes modified in accordance
with
[[Page 61542]]
similar STC's, inspections revealed a number of fasteners with both
short edge margins and short spacing in the cargo door cutout external
doublers. Some edge margins were as small as one fastener diameter.
Fasteners that are placed too close to the edge of a structural member
or spaced too close to an adjacent fastener can result in inadequate
joint strength and stress concentrations, which may result in fatigue
cracking of the skin. If such defects were to exist in the structure of
the door or the fuselage to which the main deck cargo door hinge is
attached, the attachment of the hinge could fail, and consequently
cause the door to open while the airplane is in flight.
Since unsafe conditions have been identified that are likely to
exist or develop on other products of this same type design, this
proposed AD would require, within 250 flight cycles after the effective
date of the AD, a one-time detailed visual inspection of the external
surface of the main deck cargo door hinge (both fuselage and door side
hinge elements) to detect cracks, and repair, if necessary.
Accomplishment of this inspection will ensure that the subject
airplanes are not in immediate risk of hinge failure.
In addition, the proposed AD would require a detailed visual
inspection of the mating surfaces of both the hinge and the door skin
and external fuselage doubler underlying the hinge to detect cracks or
other discrepancies (e.g., double or closely drilled holes, corrosion,
chips, scratches, or gouges). The proposed AD also would require
installation of a main deck cargo door hinge that complies with the
applicable requirements of CAR part 4b, including fail-safe
requirements. Accomplishment of this detailed visual inspection will
ensure the integrity of the door and fuselage structure to which the
hinge is attached. The proposed compliance time for this inspection and
installation is within 36 months or 4,000 flight cycles after the
effective date of this AD, whichever occurs first. The compliance time
is based on the FAA's assessment of the reasonable amount of time to
redesign, manufacture, and install a fail-safe hinge. This time is in
consideration of the 18-month time period estimated by the Boeing 727
industry working group, which includes operators, affected STC holders,
and engineering organizations, to develop FAA-approved redesigns. These
actions would be required to be accomplished in accordance with a
method approved by the FAA.
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 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 during
takeoff, these two accidents serve 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 Director-Airworthiness and Technical Standards of ATA
(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.
Applying the applicable requirements of CAR part 4b and design
criteria provided by the FAA Memorandum, the FAA has reviewed the
original type design of major transport airplanes, including Boeing 727
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:
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 93-20-02, amendment 39-8709 (58 FR 471545, October 18, 1993);
For certain Boeing Model 747-100 and -200 series
airplanes: AD 96-01-51, amendment 39-9492 (61 FR 1703, January 23,
1996); and
For certain Boeing Model 727-100 and -200 series
airplanes: AD 96-16-08, amendment 39-9708 (61 FR 41733, August 12,
1996).
Using the criteria specified in the ATA Final Report and the FAA
Memorandum as evaluation guides, the FAA conducted an engineering
design review and inspection of an airplane modified in accordance with
STC ST00015AT (held by Kitty Hawk). The FAA identified a number of
design features of the main deck cargo door systems of this STC that
are unsafe and do not meet the criteria specified in the ATA Final
Report and the FAA Memorandum. The FAA design review team 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 ST00015AT, the FAA
considers the following three specific design deficiencies of the main
deck cargo door systems to be unsafe:
1. Means to Visually Inspect the Locking Mechanism
The three view ports installed in accordance with STC ST00015AT are
located for viewing locking pins at the No. 2, No. 4, and No. 6 latch
positions of the main deck cargo door. These view ports are intended to
allow the flight crew to conduct a visual inspection of the cargo door
locking mechanism to determine whether or not the cargo door is closed,
latched, and locked. The view
[[Page 61543]]
ports are used in conjunction with the door warning system and should
provide a suitable back-up for confirming that the door is closed,
latched and locked in the event that the main deck cargo door warning
system malfunctions.
However, during the FAA design review, it was determined that these
view ports are installed at an angle; therefore, a visual inspection of
the locking pins is not possible. Therefore, the FAA finds that these
view ports cannot be used to confirm that the door is closed, latched,
and locked when the cargo door warning system malfunctions.
As discussed in the ATA Final Report and the FAA Memorandum, there
must 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.
2. Means to Prevent Pressurization to an Unsafe Level
Boeing 727-200 airplanes modified in accordance with STC ST00015AT
are configured to utilize two outward opening vent doors for the
purpose of preventing pressurization of the airplane to an unsafe level
in the event the main deck cargo door is not closed, latched, and
locked. Because the vent door openings are approximately six inches in
diameter, the opening area may be insufficient to prevent
pressurization of the airplane to an unsafe level in the event the main
deck cargo door is not closed, latched, and locked. Paragraph (1)(d) of
Appendix 1 describes the requirement that a warning indication be
provided to the door operators station to monitor the door condition.
Another function of the vent doors, if properly designed, would be to
provide such a visual warning indication. If the vent door is open, the
door operator will know the door is not closed, locked, and latched.
The vent doors in this design are not spring loaded to the fully open
position. As a result, they may appear to be closed when in fact they
are not. Rather than provide a positive indication of a safe door, they
can create a false indication of the door status. Therefore, the
position of these vent doors cannot be used to indicate that the main
cargo door is closed, latched, and locked, nor that there is a
malfunction in the vent door system.
``Failure Mode and Effects Analysis (FMEA) for B727-200 Cargo Door
Modifications,'' dated November 20, 1991, was prepared by the STC
holder as a qualitative safety analysis for the vent door system of
this STC. The FMEA indicates that the system has single point failures
of the vent door systems that can result in a false indication that the
door is safe. The presence of single point failures reflects that the
system does not meet the standard established in the ATA Final Report
and FAA memorandum that a false indication of a closed, latched, and
locked condition is improbable.
3. Powered Lock Systems
The main deck cargo door actuation control system for STC ST00015AT
utilizes a powered lock system. The main deck cargo door control system
for STC ST00015AT that utilizes electrical interlock switches is
designed to remove door control power (electrical and hydraulic) prior
to flight and to prevent inadvertent door openings. The design shows
the likelihood that latent and/or single point failures can restore or
continue to allow power to the door controls and cause inadvertent door
openings. The failure modes may be found in the electrical portion of
the door control panel, which, in turn, activates the door control
hydraulics. The potential for the occurrence of these failure
conditions is increased by the harsh operating environment of freighter
airplanes. Door system components are routinely exposed to
precipitation, dirt, grease, and foreign object intrusion, all of which
increase the likelihood of damage. As a result, wires, switches, and
relays have a greater potential to fail or short circuit in such a way
as to allow the cargo door to be powered open without an operator's
command and regardless of electrical interlock positions.
A systems safety analysis would normally evaluate and resolve the
potential for these types of unsafe conditions. However, the design
data for STC ST00015AT includes a systems safety analysis that is
insufficient to show that an inadvertent opening of the main deck cargo
door after it is fully closed, latched, and locked is extremely
improbable. The need for a system safety analysis is identified in the
ATA Final Report and the FAA Memorandum.
Since unsafe conditions have been identified that are likely to
exist or develop on other products of this same type design, this
proposed AD would require, within 60 days after the effective date,
revising the Limitations Section of the FAA-approved Airplane Flight
Manual (AFM) Supplement to provide the flight crew with procedures for
ensuring that the main deck cargo door is closed, latched, and locked
prior to dispatch of the airplane; and installing any associated
placards.
In addition, the proposed AD would require, within 36 months after
the effective date of the AD, incorporation of redesigned main deck
cargo door systems (e.g., power control, view ports, and means to
prevent pressurization to an unsafe level if the main deck cargo door
is not closed, latched, and locked), including any associated
procedures and placards that comply with the applicable requirements of
CAR part 4b and design criteria of the ATA Final Report and the FAA
Memorandum. Design data provided in support of the door systems re-
design should include a Systems Safety Analysis and Instructions for
Continued Airworthiness that are acceptable to the FAA. Accomplishment
of the incorporation of redesigned main deck cargo door systems will
prevent rapid decompression and/or structural damage to the airplane as
a result of loss or opening of the cargo door while the airplane is in
flight. The compliance time is based on the FAA's assessment of the
reasonable amount of time to incorporate redesigned main deck cargo
door systems. This time is in consideration of the 18-month time period
estimated by the Boeing 727 industry working group, which includes
operators, affected STC holders, and engineering organizations, to
develop FAA-approved redesigns.
These actions would be required to be accomplished in accordance
with a method approved by the FAA.
Cargo Barrier
In order to ensure the safety of occupants during emergency landing
conditions, the FAA first established in 1934, a set of inertia load
factors used to design the structure for restraining items of mass in
the fuselage. Because the airplane landing speeds have increased over
the years as the fleet has transitioned from propeller to jet design,
inertia load factors were changed as specified in CAR part 4b.260.
Experience has shown that an airplane designed to this regulation has a
reasonable probability of protecting its occupants from serious injury
in an emergency landing. The 727 passenger airplane was designed to
these criteria which specified an ultimate inertia load requirement of
9g in the forward direction. This criteria was applied to the seats and
structure restraining the occupants, including the flight crew, as well
as other items of mass in the fuselage.
When the 727 passenger airplane is converted to carry cargo on the
main deck, a cargo barrier is required, since most cargo containers and
the container-to-floor attaching devices are not
[[Page 61544]]
designed to withstand emergency landing loads. In fact, the FAA
estimates that the container-to-floor attaching devices will only
support approximately 1.5g's to 3g's in the forward direction. Without
a 9g cargo barrier, it is probable that the loads associated with an
emergency landing would cause the cargo to become unrestrained and
impact the occupants of the airplane, which could result in serious
injury or death.
The structural inadequacy of the cargo barrier was evident to the
FAA during its review in October 1996 of a Boeing 727 modified in
accordance with STC ST00015AT. The observations revealed that the
design of the cargo barrier floor attachment and circumferential
supporting structure does not provide adequate strength to withstand
the 9g forward inertia load generated by the main deck cargo mass, nor
does it provide a load path to effectively transfer the loads from the
cargo barrier to the fuselage structure of the airplane. These
observations are supported by data contained in ``ER 2785, Structural
Substantiation of the 50k 9g Bulkhead Restraint System in Support of
STC SA1543SO PN 53-1292-401 for the 9g Bulkhead 53-1980-300 Assembly
with Upper Attachment Structure, Lower Attachment Structure, Floor
Shear Web Structure, Seat Track Splice Fittings, Seat Tracks, and Seat
Track Splices,'' dated September 29, 1996, by M. F. Daniel. Although
this report was specific to STC SA1543SO, the FAA has determined that
the data are applicable to airplane modified in accordance with STC
ST00015AT because the design principles for attachment of the barriers
in both STC's are the same. The report reveals that structural
deficiencies were found in the net attach plates and floor attachment
structure of the cargo barrier. The data show large negative margins of
safety, which indicate that the inertia load capability of the cargo
barrier is closer to 2g than the required 9g in the forward direction.
From these analyses, it is evident that the cargo barrier would not be
capable of preventing serious injury to the occupants during an
emergency landing event with the full allowable cargo load.
Since unsafe conditions have been identified that are likely to
exist or develop on other products of this same type design, this
proposed AD would require installation of a main deck cargo barrier
that complies with the applicable requirements of CAR part 4b.
Accomplishment of the installation will prevent serious injury to the
occupants in the event of an emergency landing. The proposed compliance
time for the installation is within 36 months or 4,000 flight cycles
after the effective date of the AD, whichever occurs first. This
compliance time is based on the FAA's assessment of the reasonable
amount of time to redesign, manufacture, and install the cargo barrier.
This time is consistent with estimates by affected STC holders and
operators that necessary redesigns can by developed and approved by the
FAA within 12 to 18 months from August 1998.
Regulatory Evaluation Summary
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.
This analysis examines the cost of a proposed AD that would require
the installation of a fail-safe hinge, redesigned main deck cargo door
warning and power control systems, and a 9g cargo barrier on Boeing
Model 727 series airplanes that have been modified in accordance with
an STC held by Kitty Hawk Air Cargo. As discussed above, the FAA has
determined that the main deck cargo door hinge is not fail-safe, that
certain main deck cargo door control systems do not provide an adequate
level of safety, and that the main deck cargo barrier is not
structurally adequate during a minor crash landing.
Approximately 5 U.S.-registered Boeing Model 727 series airplane
would be affected by the proposed AD. Kitty Hawk, owner of the STC,
operates all of these airplanes. The following discussion addresses, in
sequence, the actions in proposed Rules Docket No. 97-NM-234-AD and the
estimated cost associated with each of these actions. An analysis of
the estimated cost is also available in the Rules Docket.
1. Main Deck Cargo Door Hinge
Since unsafe conditions have been identified that are likely to
exist or develop on other modified Boeing Model 727 series airplanes,
paragraph (a) of the proposed AD would require, within 250 flight
cycles after the effective date this AD, a one-time detailed visual
inspection to detect cracks of the external surface of the main deck
cargo door hinge.
Paragraph (b)(1) of the proposed AD would require, within 36 months
or 4,000 cycles after the effective date of this AD, a detailed visual
inspection of the mating surfaces of both the hinge and the door skin
and external fuselage doubler underlying the hinge. The FAA estimates
that compliance with this inspection would take 200 hours at a cost of
$12,000 per airplane, or $600,000 for the affected fleet. Kitty Hawk
estimates that compliance with these two inspections would cost
approximately $1,430 per airplane, or $7,150 for the affected fleet.
Paragraph (b)(2) of the proposed AD would require installation of a
fail-safe door hinge. The compliance time for this installation also
would be 36 months or 4,000 cycles after the effective date this AD.
Kitty Hawk estimates the cost to design and certificate such a hinge is
$50,000, that no parts for a fail-safe door hinge would be required,
and that the cost of the modification would cost $15,000. Total
compliance costs for this proposed provision for the affected fleet of
5 airplanes would be $125,000.
Paragraph (c) of the proposed AD would require that, if any cracks
or discrepancies are detected during the inspections required by
paragraph (a) or (b)(1) of the proposed AD, repairs must be made prior
to further flight. The cost of these repairs is not attributable to
this proposed AD.
For purposes of this analysis, the FAA assumes an effective date of
July 1, 2000. The cost to comply with proposed paragraphs (a) through
(c) over the 36-month compliance period is $132,000 or $116,000
discounted to present value at 7 percent. The FAA assumes that the
installation of the main deck cargo door hinge [paragraph (b)(1)] would
be accomplished at the same time as the detailed visual inspection of
fastener holes [paragraph (b)(2)]. The FAA also assumes that Kitty Hawk
would perform these two activities uniformly throughout the 36-month
period. Finally, the certification cost for the main deck cargo door
hinge would be incurred within the first 6 months after the effective
date of this AD.
2. Main Deck Cargo Door Systems
Paragraph (d) of the proposed AD would require, within 60 days
after the effective date of this AD, a revision to the Limitations
Section of the FAA-approved AFM Supplement by inserting procedures to
ensure that the main deck cargo door is closed, latched, and locked
prior to dispatch of the airplane. In addition, paragraph (d) of the
proposed AD would require the installation of any associated placards.
The FAA assumes that Boeing Model 727 series airplanes converted
under a
[[Page 61545]]
Kitty Hawk STC will have an acceptable pressurization vent door
installed, which operators could use to visually determine whether the
vent is in the proper position prior to dispatch, indicating that the
door is closed, latched, and locked. The FAA estimates that this
activity would take no more than 30 minutes. Assuming each affected
airplane flies one flight per day, 260 days per year, the estimated
cost per inspection would be $30, or $7,800 per airplane per year until
the door system is changed, a total of $58,500 over 36 months.
Paragraph (e) of the proposed AD would require, within 36 months
after the effective date of this AD, incorporation of a redesigned main
deck cargo door system. Kitty Hawk estimates that the development and
certification of the system would cost $175,000. Modification parts
would cost $38,000 per airplane and labor costs would be $23,500 per
airplane. The FAA assumes that operators would incorporate the
redesigned main deck cargo door system during regularly scheduled
maintenance. (Kitty Hawk indicates that any lost revenue due to
additional down time should be attributed to the installation of the 9g
main deck cargo barrier, discussed below.) The total costs of
installing a redesigned main deck cargo door system, including
certification, parts, and labor would be $482,500 over the 36-month
period.
The total estimated cost to comply with proposed requirements for
the main deck cargo door system is $541,000 or $523,000, discounted to
present value.
3. Main Deck Cargo Barrier
Paragraph (f) of the proposed AD would require, within 36 months or
4,000 flight cycles after the effective date of this AD, installation
of a main deck cargo barrier that complies with the applicable
requirements of CAR part 4b. Ventura Aerospace holds an STC for an
approved 9g barrier, and Kitty Hawk indicates that they may purchase
barriers manufactured to this STC. The cost of the barrier kits is
$67,500. Kitty Hawk estimates that labor would cost $13,500 per
airplane and that an affected airplane would be out-of-service 3
additional days, at a cost of $15,000 per day, while this barrier is
installed.
The FAA assumes that Kitty Hawk would install 9g barriers uniformly
over the 36-month compliance period. The total non-discounted cost of
this proposed requirement would be $630,000, or $551,000 discounted to
present value.
4. Alternative Methods of Compliance (AMOC) and Special Flight Permits
Paragraph (g) of the proposed AD would allow an AMOC or adjustment
of compliance time that provides an acceptable level of safety if
approved by the Manager of the Atlanta ACO. The FAA is unable to
determine the cost of an AMOC, but assumes it would be less than the
cost of complying with the proposed provisions in paragraphs (a)
through (f) of the proposed AD.
Paragraph (h) of the proposed AD would allow special flight permits
in accordance with the regulations to operate an affected airplane to a
location where the requirements of the proposed AD could be
accomplished.
5. Total Cost of the Proposed AD
The FAA estimates that the total compliance cost of the proposed AD
would be $1.3 million, or $1.2 million discounted to present value.
The Regulatory Flexibility Act (RFA) of 1980 establishes ``as a
principle of regulatory issuance that agencies shall endeavor,
consistent with the objective of the rule and of applicable statutes,
to fit regulatory and informational requirements to the scale of the
business, organizations, and governmental jurisdictions subject to
regulation. To achieve that principle, the RFA requires agencies to
solicit and consider flexible regulatory proposals and to explain the
rationale for their actions. The RFA covers a wide-range of small
entities, including small businesses, not-for-profit organizations, and
small governmental jurisdictions.
Agencies must perform a review to determine whether a proposed or
final rule will have a significant economic impact on a substantial
number of small entities. If the determination is that it will, the
Agency must prepare a regulatory flexibility analysis as described in
the RFA. However, if an agency determines that a proposed or final rule
is not expected to have a significant economic impact on a substantial
number of small entities, section 605(b) of the RFA provides that the
head of the agency may so certify and an RFA is not required. The
certification must include a statement providing the factual basis for
this determination, and the reasoning should be clear.
Only one operator, Kitty Hawk, would be affected by this proposed
AD. Kitty Hawk is small, that is, it employs fewer than 1,500 persons.
However, pursuant to the Regulatory Flexibility Act, 5 U.S.C. 605(b),
the FAA certifies that this proposed AD would not have a significant
economic impact on a substantial number of small entities, because one
entity is not a substantial number.
Title II of the Unfunded Mandates Reform Act of 1995 (the Act),
enacted as Pub. L. 104-4 on March 22, 1995, requires each Federal
agency, to the extent permitted by law, to prepare a written assessment
of the effects of any Federal mandate in a proposed or final agency
rule that may result in the expenditure by State, local, and tribal
governments, in the aggregate, or by the private sector, of $100
million or more (adjusted annually for inflation) in any one year.
Section 204(a) of the Act, 2 U.S.C. 1534(a), requires the Federal
agency to develop an effective process to permit timely input by
elected officers (or their designees) of State, local, and tribal
governments on a proposed ``significant intergovernmental mandate.'' A
``significant intergovernmental mandate'' under the Act is any
provision in a Federal agency regulation that would impose an
enforceable duty upon State, local, and tribal governments, in the
aggregate, of $100 million (adjusted annually for inflation) in any one
year. Section 203 of the Act, 2 U.S.C. 1533, which supplements section
204(a), provides that before establishing any regulatory requirements
that might significantly or uniquely affect small governments, the
agency shall have developed a plan that, among other things, provides
for notice to potentially affected small governments, if any, and for a
meaningful and timely opportunity to provide input in the development
of regulatory proposals.
This proposed AD does not contain any Federal intergovernmental or
private sector mandate. Therefore, the requirements of Title II of the
Unfunded Mandates Reform Act of 1995 do not apply.
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.
[[Page 61546]]
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
Boeing: Docket 97-NM-234-AD.
Applicability: Model 727 series airplanes that have been
converted from a passenger to a cargo-carrying (``freighter'')
configuration in accordance with Supplemental Type Certificate (STC)
ST00015AT, 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 (g) 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 structural failure of the main deck cargo door hinge
or failure of the cargo door systems, which could result in the loss
or opening of the cargo door while the airplane is in flight, rapid
decompression, and structural damage to the airplane; and to prevent
failure of the main deck cargo barrier during an emergency landing,
which could injure occupants; accomplish the following:
Actions Addressing the Main Deck Cargo Door Hinge
(a) Within 250 flight cycles after the effective date of this
AD, perform a detailed visual inspection of the external surface of
the main deck cargo door hinge (both fuselage and door side hinge
elements) to detect cracks.
Note 2: For the purposes of this AD, a detailed visual
inspection is defined as: ``An intensive visual examination of a
specific structural area, system, installation, or assembly to
detect damage, failure, or irregularity. Available lighting is
normally supplemented with a direct source of good lighting at
intensity deemed appropriate by the inspector. Inspection aids such
as mirror, magnifying lenses, etc., may be used. Surface cleaning
and elaborate access procedures may be required.''
(b) Within 36 months or 4,000 flight cycles after the effective
date of this AD, whichever occurs first, accomplish paragraphs
(b)(1) and (b)(2) of this AD.
(1) Perform a detailed visual inspection of the mating surfaces
of both the hinge and the door skin and external fuselage doubler
underlying the hinge to detect cracks or other discrepancies (e.g.,
double or closely drilled holes, corrosion, chips, scratches, or
gouges). The detailed visual inspection shall be accomplished in
accordance with a method approved by the Manager, Los Angeles
Aircraft Certification Office (ACO), FAA, Transport Airplane
Directorate. The requirements of this paragraph may be accomplished
prior to or concurrently with the requirements of paragraph (b)(2)
of this AD.
(2) Install a main deck cargo door hinge that complies with the
applicable requirements of Civil Air Regulations (CAR) part 4b,
including fail-safe requirements, in accordance with a method
approved by the Manager, Los Angeles ACO.
(c) If any crack or discrepancy is detected during the detailed
visual inspection required by either paragraph (a) or (b)(1) of this
AD, prior to further flight, repair in accordance with a method
approved by the Manager, Los Angeles ACO.
Actions Addressing the Main Deck Cargo Door Systems
(d) Within 60 days after the effective date of this AD, revise
the Limitations Section of the FAA-approved Airplane Flight Manual
(AFM) Supplement by inserting therein procedures to ensure that the
main deck cargo door is closed, latched, and locked prior to
dispatch of the airplane, and install any associated placards. The
AFM revision procedures and installation of any associated placards
shall be accomplished in accordance with a method approved by the
Manager, Los Angeles ACO.
(e) Within 36 months after the effective date of this AD,
incorporate redesigned main deck cargo door systems (e.g., power
control, view ports, and means to prevent pressurization to an
unsafe level if the main deck cargo door is not closed, latched, and
locked), including any associated procedures and placards, that
comply with the applicable requirements of CAR part 4b and criteria
specified in Appendix 1 of this AD; in accordance with a method
approved by the Manager, Los Angeles ACO.
Note 3: The design data submitted for approval should include a
Systems Safety Analysis and Instructions for Continued Airworthiness
that are acceptable to the Manager, Los Angeles ACO.
Actions Addressing the Main Deck Cargo Barrier
(f) Within 36 months or 4,000 flight cycles after the effective
date of this AD, whichever occurs first, install a main deck cargo
barrier that complies with the applicable requirements of CAR part
4.b, in accordance with a method approved by the Manager, Los
Angeles ACO.
Note 4: The maximum main deck total payload that can be carried
is limited to the lesser of the approved cargo barrier weight limit,
weight permitted by the approved maximum zero fuel weight, weight
permitted by the approved main deck position weights, weight
permitted by the approved main deck running load or distributed load
limitations, or approved cumulative zone or fuselage monocoque
structural loading limitations (including lower hold cargo).
Note 5: Installation of a Ventura Aerospace Inc. cargo barrier
STC ST00848LA is an approved means of compliance with the
requirements of paragraph (f) of this AD.
(g) An alternative method of compliance or adjustment of the
compliance time contained in this proposal 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 6: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Los Angeles ACO.
(h) 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:
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.
[[Page 61547]]
(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 November 4, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 99-29475 Filed 11-10-99; 8:45 am]
BILLING CODE 4910-13-U
