[Federal Register Volume 60, Number 237 (Monday, December 11, 1995)]
[Proposed Rules]
[Pages 63465-63468]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-30074]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 94-NM-226-AD]
Airworthiness Directives; Boeing Model 747 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Supplemental notice of proposed rulemaking; reopening of
comment period.
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SUMMARY: This document revises an earlier proposed airworthiness
directive (AD), applicable to certain Boeing Model 747 series
airplanes, that would have required modification of the left and right
inboard elevator servo assemblies and the hydraulic routing of the
right inboard elevator power control package (PCP). That proposal was
prompted by a report of an uncommanded right elevator deflection after
takeoff and reports of elevator/control column bumps during landing
gear retraction on these airplanes. This action revises the proposed
rule by revising the applicability of the proposed AD to add additional
airplanes and additional part numbers of the elevator PCP's, and by
including additional service information. The actions specified by this
proposed AD are intended to prevent uncommanded elevator deflection,
which could result in structural damage and reduced controllability of
the airplane.
DATES: Comments must be received by January 5, 1996.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 94-NM-226-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; and Parker Hannifin Corporation, Customer
Support Operations, 16666 Von Karman Avenue, Irvine, California 92714.
This information may be examined at the FAA, Transport Airplane
Directorate, 1601 Lind Avenue, SW., Renton, Washington.
FOR FURTHER INFORMATION CONTACT: Kathi N. Ishimaru, Aerospace Engineer,
[[Page 63466]]
Systems and Equipment Branch, ANM-130S, FAA, Transport Airplane
Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue,
SW., Renton, Washington 98055-4056; telephone (206) 227-2674; fax (206)
227-1181.
SUPPLEMENTARY INFORMATION:
Comments Invited
Interested persons are invited to participate in the making of the
proposed rule by submitting such written data, views, or arguments as
they may desire. Communications shall identify the Rules Docket number
and be submitted in triplicate to the address specified above. All
communications received on or before the closing date for comments,
specified above, will be considered before taking action on the
proposed rule. The proposals contained in this notice may be changed in
light of the comments received.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the proposed rule. All
comments submitted will be available, both before and after the closing
date for comments, in the Rules Docket for examination by interested
persons. A report summarizing each FAA-public contact concerned with
the substance of this proposal will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this notice must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket Number 94-NM-226-AD.'' The postcard will be date stamped and
returned to the commenter.
Availability of NPRMs
Any person may obtain a copy of this NPRM by submitting a request
to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules
Docket No. 94-NM-226-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
A proposal to amend part 39 of the Federal Aviation Regulations (14
CFR part 39) to add an airworthiness directive (AD), applicable to
certain Boeing Model 747 series airplanes, was published as a notice of
proposed rulemaking (NPRM) in the Federal Register on March 3, 1995 (60
FR 11942). That NPRM would have required modification of the left and
right inboard elevator servo assemblies and re-routing the hydraulic
tubing of the inboard elevator power control package (PCP). That NPRM
was prompted by a report of an uncommanded right elevator deflection
after takeoff and reports of elevator/control column bumps during
landing gear retraction on these airplanes. That condition, if not
corrected, could result in structural damage and reduced
controllability of the airplane.
Due consideration has been given to the comments received in
response to the NPRM.
One commenter requests that paragraph (a) of the proposal be
revised to cite the latest revision of Boeing Alert Service Bulletin
747-27A2348 when referring to the applicability of that paragraph. This
commenter states that Revision 1 of the service bulletin includes
additional airplanes that are also subject to the proposed AD. The FAA
concurs. The FAA inadvertently cited the original version, dated
November 17, 1994, of Boeing Alert Service Bulletin 747-27A2348 in
paragraph (a) of the proposal when referring to the applicable
airplanes for that paragraph. Since that revision level is incorrect,
the FAA has removed it and referenced Revision 1, dated January 26,
1995, in its place in paragraph (a) of the supplemental NPRM.
One commenter states that Model 747SP series airplanes should be
subject to paragraph (b) of the proposal. The FAA acknowledges that
Model 747SP series airplanes were inadvertently omitted from the
applicability of the proposal. The FAA's intent was that the proposed
rule be applicable to all Model 747 series airplanes (i.e., Model 747-
100, -200B, -200F, -200C, 747SR, 747SP, 747-100B, -300, -100B SUD, -
400, -400D, and -400F series airplanes). Therefore, the FAA has revised
the applicability statement of the supplemental NPRM accordingly.
Since these changes expand the scope of the originally proposed
rule, the FAA has determined that it is necessary to reopen the comment
period to provide additional opportunity for public comment.
In addition, due consideration has been given to the following
additional comments, which do not change the scope of the originally
proposed rule, received in response to the NPRM.
Three commenters request that the compliance time for paragraph (a)
of the proposal be extended from the proposed 1 year. One of these
commenters states that such an extension will allow operators to
accomplish the modification during a regularly scheduled heavy
maintenance visit. The FAA does not concur. In developing an
appropriate compliance time for this action, the FAA considered not
only the degree of urgency associated with addressing the subject
unsafe condition, but the availability of required parts and the
practical aspects of installing the required modification within an
interval of time that parallels normal scheduled maintenance for the
majority of affected operators. The manufacturer has advised that an
ample number of required parts should be available for modification of
the U.S. fleet within the proposed compliance period. Further, the FAA
has determined that a heavy maintenance visit is not required to
accomplish the modification.
Several commenters state that paragraph (b) of the proposed rule is
unjustified because there have been no reports of actuator jamming on
the classic Model 747 (747-100, -100B SUD, -200, -300, SR, SP) series
airplanes after accumulating 87 million flight hours. One of these
commenters states that the safety concern surrounding the configuration
of the servo valve assembly of the inboard elevator PCP is theoretical
at best.
The FAA does not concur with the commenters' suggestion that
paragraph (b) of the proposed rule is unjustified. The FAA finds that
the lack of reported jams and subsequent uncommanded elevator motion
may be attributed, in part, to the small percentage of airplanes that
recorded the elevator position while accumulating the 87 million flight
hours. Paragraph (c)(10) of section 121.343, ``Flight recorders'', of
the Federal Aviation Regulations (FAR) (14 CFR 121.343) requires that
operators record either the control column or pitch control surface
position (i.e., the position of the elevator and the stabilizer) of the
airplane. Operators may comply with section 121.343 by electing to
record the control column position, which is not a positive indicator
of the elevator position. Consequently, incidents of uncommanded
elevator motion due to actuator jamming may have occurred, but were not
reported due to the flightcrew's inability to confirm the anomaly.
Furthermore, the FAA finds that uncommanded elevator motion may occur
on all Boeing Model 747 series airplanes if the servo valve secondary
slide moves to the valve's internal stop. Therefore, the FAA finds that
this AD action is warranted since an unsafe condition exists, which is
identified as reduced controllability or structural damage to the
airplane due to asymmetric elevator.
One commenter states that only Model 747-400 series airplanes have
experienced actuator jamming with uncommanded elevator deflection. The
commenter also states that the uncommanded elevator deflection problem
has been directly attributed to
[[Page 63467]]
the fact that Model 747-400 series airplanes have the hydraulic system
number 4 connected to the pressure sensitive side of the servo valve of
the right inboard elevator PCP. The commenter contends that rerouting
the hydraulic tubing, as required by paragraph (a) of the proposal
(which references Boeing Alert Service Bulletin 747-27A2348, Revision
1, dated January 26, 1995, as the appropriate source of service
information) will alleviate this problem. The commenter notes that
Model 747-100, -200, -300, and SP series airplanes, which do not have
the hydraulic system number 4 connected to the pressure sensitive side
of the servo valve of the right inboard elevator PCP, have not
experienced the uncommanded elevator deflection problem.
From this comment, the FAA infers that the commenter is requesting
that paragraph (b) of the proposal be deleted. The FAA does not concur.
The FAA has reviewed the pressure survey data for the number 3 and
number 4 systems that was submitted by another commenter. The FAA finds
that pressure fluctuations, which contribute to uncommanded elevator
deflection, occur in hydraulic system number 3, as well as hydraulic
system number 4. Therefore, the FAA finds that these data do not
substantiate the commenter's suggestion that routing the hydraulic
system number 3 to the sensitive side of the servo valve would preclude
uncommanded elevator deflection.
One commenter states that paragraph (b) of the proposal, which is
applicable to certain Model 747-100, -200, -300, and -400 series
airplanes, references Parker Service Bulletin 327400-27-171 as the
appropriate source of service information. The commenter further states
that this service bulletin is not applicable to certain Model 747-100,
-100B SUD, -200, -300, SR, and SP series airplanes, since the elevator
power control packages specified in Parker Service Bulletin 327400-27-
171 are not installed on these airplanes. The FAA's intent was to
reference a service bulletin that addressed a modification for all
affected airplane models. The FAA has reviewed and approved Parker
Service Bulletin 93600-27-173, dated May 17, 1995. The modification
procedures described in this service bulletin are identical to those
described in Parker Service Bulletin 327400-27-171. The effectivity
listing of Parker Service Bulletin 93600-27-173 contains elevator PCP's
having part numbers
(P/N) 93600-5005 through -5051 inclusive, which are installed on
certain Model 747-100, -100B SUD, -200, -300, SR, and SP series
airplanes. The FAA has revised the applicability statement of the
supplemental NPRM to include these additional P/N's. Additionally, the
FAA has revised paragraph (b) of the supplemental NPRM to include this
service bulletin as an additional source of service information.
One commenter requests that applicability of paragraph (b) of the
proposal be limited to Model 747-100, -100B SUD, -200, -300, SR, and SP
series airplanes (``classic'') having cumulative line (C/L) 696 and
subsequent and that the compliance time be extended from 3 years to 5
years for those airplanes. The commenter contends that the aft fuselage
limit load can be exceeded if the residual pressure at the actuator
pistons exceeds 800 pounds per square inch (psi)/cylinder. The
commenter further contends that the probability of exceeding this is
less than 1 x 10e-5. This pressure assumes the valve jammed at the
most adverse position achievable from pilot inputs. The commenter
states that the aft fuselage limit load can be exceeded for classic
airplanes having C/L 001 through 695 inclusive, if the residual
pressure at the actuator pistons exceeds 1,700 psi/cylinder. The
commenter also states that the probability of exceeding the structural
limit is less than 1 x 10e-9.
The FAA does not concur with the commenter's request to limit the
applicability and extend the compliance time of paragraph (b) of the
proposal. Following a review of the commenter's probability analysis,
the FAA has determined that the commenter has based its analysis on a
sampling that was much too small from which accurate statistical
conclusions that would be representative of the fleet could be drawn.
Further, the FAA finds that the flow rate and differential pressures
used by this commenter were not substantiated to be the worst case
scenario. Therefore, based on this flawed probability analysis, no
change to the supplemental NPRM is warranted.
One commenter requests that Boeing Model 747-400 series airplanes
be removed from the applicability of paragraph (b) of the proposal. The
commenter states that if the valve jams, the resultant asymmetric
elevator will not result in structural damage on these airplanes. The
FAA does not concur. The FAA has determined that, although the
asymmetric elevator may not damage Model 747-400 series airplanes, an
unsafe condition (i.e., reduced controllability) still exists.
Two commenters request that the compliance time for paragraph (b)
of the proposal be extended from the proposed 3 years to 5 years. One
commenter states that it does not have enough seed units to accomplish
the modification at their own facilities within the proposed compliance
time. The FAA does not concur. As stated above, the FAA considered the
availability of required parts and the practical aspects of installing
the required modification. In addition, the FAA finds that other
maintenance facilities are available to operators that are unable to
accomplish the modification at their own facilities. However, under
paragraph (c) of the proposed rule, the FAA may approve requests for
adjustments to the compliance time if data are submitted to
substantiate that such an adjustment would provide an acceptable level
of safety.
One commenter questions the FAA's estimate of the cost of required
replacement parts for classic Model 747 series airplanes. The commenter
states that the $3,720 per airplane figure, presented in the cost
impact information in the preamble to the notice, is too low. This
commenter suggests that parts costs will be approximately $7,440 per
airplane (2 elevator power control packages at $3,720 each). After
considering the data presented by the commenter, the FAA concurs that
the cost of required parts per airplane is higher than previously
estimated; the economic impact information, below, has been revised to
indicate this higher amount.
There are approximately 672 Model 747-100, -100B SUD, -200, -300,
SR, and SP series airplanes, and 357 Model 747-400 series airplanes of
the affected design in the worldwide fleet, a total of 1,029 airplanes.
The FAA estimates that 114 Model 747-100, -100B SUD, -200, -300,
SR, and SP series airplanes of U.S. registry would be affected by this
proposed AD, that it would take approximately 73 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
$7,440 per airplane. Based on these figures, the cost impact of the
proposed AD on U.S. operators is estimated to be $1,347,480, or $11,820
per airplane.
The FAA estimates that 65 Model 747-400 series airplanes of U.S.
registry would be affected by this proposed AD, that it would take
approximately 111 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 $12,269 per airplane. Based on these
figures, the cost impact
[[Page 63468]]
of the proposed AD on U.S. operators is estimated to be $1,230,385, or
$18,929 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.
The regulations proposed herein would not have substantial direct
effects on the States, on the relationship between the national
government and the States, or on the distribution of power and
responsibilities among the various levels of government. Therefore, in
accordance with Executive Order 12612, it is determined that this
proposal would not have sufficient federalism implications to warrant
the preparation of a Federalism Assessment.
For the reasons discussed above, I certify that this proposed
regulation (1) is not a ``significant regulatory action'' under
Executive Order 12866; (2) is not a ``significant rule'' under the DOT
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979);
and (3) if promulgated, will not have a significant economic impact,
positive or negative, on a substantial number of small entities under
the criteria of the Regulatory Flexibility Act. A copy of the draft
regulatory evaluation prepared for this action is contained in the
Rules Docket. A copy of it may be obtained by contacting the Rules
Docket at the location provided under the caption ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Safety.
The Proposed Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration proposes to amend
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 USC 106(g), 40101, 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
Boeing: Docket 94-NM-226-AD.
Applicability: Model 747 series airplanes, equipped with Parker
inboard elevator power control packages (PCP) having part numbers
(P/N) 93600-5005 through -5051 inclusive, or P/N's 327400-1001, -
1003, -1005, and -1007; certificated in any category.
Note 1: This AD applies to each airplane identified in the
preceding applicability provision, regardless of whether it has been
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 use the authority
provided in paragraph (c) of this AD to request approval from the
FAA. This approval may address either no action, if the current
configuration eliminates the unsafe condition; or different actions
necessary to address the unsafe condition described in this AD. Such
a request should include an assessment of the effect of the changed
configuration on the unsafe condition addressed by this AD. In no
case does the presence of any modification, alteration, or repair
remove any airplane from the applicability of this AD.
Compliance: Required as indicated, unless accomplished
previously.
To prevent uncommanded elevator deflection, which could result
in structural damage and reduced controllability of the airplane,
accomplish the following:
(a) For Model 747-400 series airplanes, as listed in Boeing
Alert Service Bulletin 747-27A2348, Revision 1, dated January 26,
1995: Within 1 year after the effective date of this AD, modify the
hydraulic tubing of the right inboard elevator PCP, in accordance
with Boeing Alert Service Bulletin 747-27A2348, Revision 1, dated
January 26, 1995.
(b) For all airplanes: Within 3 years after the effective date
of this AD, modify the left and right servo assemblies of the
inboard elevator PCP, in accordance with Parker Service Bulletin
327400-27-171, Revision 1, dated April 14, 1995, or Parker Service
Bulletin 93600-27-173, dated May 17, 1995, as applicable.
(c) 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.
(d) 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 December 5, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 95-30074 Filed 12-8-95; 8:45 am]
BILLING CODE 4910-13-U
