[Federal Register Volume 60, Number 110 (Thursday, June 8, 1995)]
[Proposed Rules]
[Pages 30208-30211]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-14055]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 94-NM-72-AD]
Airworthiness Directives; Boeing Model 757 Series Airplanes
Equipped With Pratt & Whitney Engines
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 757 series
airplanes, that would have required inspection of certain fuse pins,
and replacement of certain fuse pins with certain other fuse pins. That
proposal was prompted by the development of new corrosion-resistant
steel fuse pins. This action revises the proposed rule by including a
requirement for inspections of refinished straight fuse pins and
replacement of cracked refinished straight fuse pins with certain other
straight fuse pins. The actions specified by this proposed AD are
intended to prevent cracking of the midspar fuse pins, which may lead
to separation of the strut and engine from the wing of the airplane.
DATES: Comments must be received by June 29, 1995.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 94-NM-72-AD, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056. Comments may be inspected at this location
between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal
holidays.
The service information referenced in the proposed rule may be
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle,
Washington 98124-2207. This information may be examined at the FAA,
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,
Washington.
FOR FURTHER INFORMATION CONTACT: Carrie Sumner, Aerospace Engineer,
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056; telephone (206) 227-2778; 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-72-AD.'' The postcard will be date stamped and
returned to the commenter. [[Page 30209]]
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-72-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 757 series airplanes, was published as a notice of
proposed rulemaking (NPRM) in the Federal Register on August 9, 1994
(59 FR 40490). That NPRM would have superseded AD 93-16-09, amendment
39-8666 (58 FR 45044, August 26, 1993) to require:
1. inspections to detect cracking of straight fuse pins,
2. replacement of cracked straight fuse pins with either new 15-5PH
corrosion- resistant steel fuse pins or like pins,
3. replacement of bulkhead fuse pins with new 15-5PH corrosion-
resistant steel fuse pins, and
4. repetitive inspections of newly-installed fuse pins.
(Installation of the new 15-5PH corrosion-resistant steel fuse pins
would allow a longer repetitive inspection interval than was previously
provided by AD 93-16-09.)
That NPRM was prompted by the development of new 15-5PH corrosion-
resistant steel fuse pins. Cracking of the midspar fuse pins, if not
detected and corrected in a timely manner, could result in separation
of the strut and engine from the wing of the airplane.
Due consideration has been given to the comments received in
response to that NPRM.
One commenter requests that the proposal be revised to clarify the
replacement requirements. The commenter questions whether straight fuse
pins may be replaced independently of the other fuse pins in the same
pylon when only one fuse pin is cracked. Further, the commenter
questions whether steel fuse pins having part number (P/N) 311N5067-1
may be installed on the same pylon as corrosion-resistant steel (CRES)
fuse pins having P/N 311N5217-1. The FAA concurs that clarification is
warranted. It is not the FAA's intent to require replacement of
uncracked fuse pins. However, the FAA has determined that it is
unacceptable to mix the types of fuse pins on the same strut since fuse
pin double shear load depends upon the type of fuse pin. Therefore, a
steel fuse pin having part number (P/N) 311N5067-1 may not be installed
on the same strut that has a corrosion-resistant steel (CRES) fuse pin
having P/N 311N5217-1 installed on that strut. However, each strut must
have fuse pins of the same type, which may differ from fuse pins on
another strut. A new paragraph (e) has been added to this supplemental
NPRM to clarify the replacement requirements.
One commenter requests that the proposal be revised to include
repetitive inspections of refinished straight fuse pins. The commenter
asserts that these pins should be inspected repetitively until cracking
is found, at which time they should be replaced with the new 15-5PH
fuse pins. The FAA concurs. The FAA's intent was to continue the
requirements of AD 93-16-09 to inspect repetitively currently installed
refinished straight fuse pins. However, this requirement was
inadvertently excluded from the originally issued NPRM; therefore, a
new paragraph (b) has been added to this supplemental NPRM to specify
this.
[All paragraphs subsequent to paragraph (b) have been redesignated
in this supplemental NPRM to accommodate the new paragraph (b).]
One commenter requests that the proposed requirement in paragraph
(b) of the NPRM, which would require replacement of the bulkhead fuse
pins within 90 days, be extended to 3,000 flight cycles. The commenter
notes that there have been no reports of cracking or corrosion on 68
bulkhead fuse pins that had accumulated between 4,500 and 6,000 flight
cycles. Further, the commenter states that its suggested 3,000-flight
cycle compliance time will not adversely affect safety, since test
results indicate that these fuse pins will maintain limit load beyond
5,000 flight cycles after the detection of an initial crack.
Additionally, the commenter asserts that the fail-safe capability of
the strut on Model 757 series airplanes can withstand full limit load
with a total failure (i.e., failure of both shear planes) of the
midspar fuse pin.
The FAA concurs. The FAA has reviewed the test data submitted by
this commenter and has determined that extending the compliance time
for replacement to 3,000 flight cycles will not adversely affect
safety, since the strut of Model 757 series airplanes has fail-safe
capability and can withstand full limit load, even with total failure
of a midspar fuse pin. Paragraph (c) of this supplemental NPRM
specifies this revised compliance time.
One commenter requests that the proposed repetitive inspection
interval of 3,000 flight cycles for inspection of the new 15-5PH fuse
pins be revised to coincide with operators' regularly scheduled
maintenance visits at 3,500 landings. The FAA concurs. The FAA finds
that extending the compliance time by 500 flight cycles will not
adversely affect safety, and will allow the modification to be
performed at a base during regularly scheduled maintenance where
special equipment and trained maintenance personnel will be available
if necessary. Therefore, paragraphs (a)(2)(ii), (d)(1), and (d)(2)(ii)
of the supplemental NPRM specify a repetitive inspection interval of
3,500 flight cycles for inspection of the new 15-5PH corrosion-
resistant steel fuse pins.
One commenter states that Boeing Service Bulletin 757-54A0019,
Revision 5, dated March 17, 1994 (which is referenced in the proposal
as the appropriate source of service information), does not describe
procedures for eddy current inspections of the new 15-5PH corrosion-
resistant steel fuse pins. Therefore, the commenter requests that the
proposal be revised to reference another source of service information
for accomplishing the eddy current inspections. The FAA does not
concur. However, since these procedures are the same as those for the
old style fuse pins, part number 311N5067-1, the FAA finds that the
procedures in the referenced service bulletin also apply to the new 15-
5PH fuse pins. Therefore, paragraph (a)(1)(ii) and (d)(2)(ii) of this
supplemental NPRM reference the procedures described in the service
bulletin to perform the eddy current inspections of the new 15-5PH
corrosion-resistant steel fuse pins.
The FAA has recently reviewed the figures it has used over the past
several years in calculating the economic impact of AD activity. In
order to account for various inflationary costs in the airline
industry, the FAA has determined that it is necessary to increase the
labor rate used in these calculations from $55 per work hour to $60 per
work hour. The economic impact information, below, has been revised to
reflect this increase in the specified hourly labor rate.
As a result of recent communications with the Air Transport
Association (ATA) of America, the FAA has learned that, in general,
some operators may misunderstand the legal effect of AD's on airplanes
that are identified in the applicability provision of the AD, but that
have been altered or repaired in the area addressed by the AD. The FAA
points out that all airplanes identified in the applicability provision
of an AD are legally subject to the AD. If an airplane has been altered
or repaired in the affected area in such a way as to affect
[[Page 30210]] compliance with the AD, the owner or operator is
required to obtain FAA approval for an alternative method of compliance
with the AD, in accordance with the paragraph of each AD that provides
for such approvals. A note has been included in this supplemental
notice to clarify this long-standing requirement.
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.
There are approximately 273 Model 757 series airplanes equipped
with Pratt & Whitney engines of the affected design in the worldwide
fleet. The FAA estimates that 237 airplanes of U.S. registry would be
affected by this proposed AD.
The inspections that were previously required by AD 93-16-09, and
retained in this supplemental proposal take approximately 8 work hours
per fuse pin at an average labor rate of $60 per work hour. There are 4
fuse pins per airplane. Based on these figures, the total cost impact
of these inspections on U.S. operators is estimated to be $455,040, or
$1,920 per airplane, per cycle. However, since the integrity and
strength of the new steel fuse pins permit longer inspection intervals,
the cost impact for these inspections would actually be lessened
because the proposed inspections are not required to be performed as
frequently as currently required by AD 93-16-09.
The proposed replacement would take approximately 56 work hours per
fuse pin at an average labor rate of $60 per work hour. (There are 4
fuse pins per airplane.) Required parts would be provided by the
manufacturer at no cost to the operator. Based on these figures, the
total cost impact of the proposed replacement on U.S. operators is
estimated to be $3,185,280, or $13,440 per airplane.
The total 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.
The FAA recognizes that the obligation to maintain aircraft in an
airworthy condition is vital, but sometimes expensive. Because AD's
require specific actions to address specific unsafe conditions, they
appear to impose costs that would not otherwise be borne by operators.
However, because of the general obligation of operators to maintain
aircraft in an airworthy condition, this appearance is deceptive.
Attributing those costs solely to the issuance of this AD is
unrealistic because, in the interest of maintaining safe aircraft, most
prudent operators would accomplish the required actions even if they
were not required to do so by the AD.
A full cost-benefit analysis has not been accomplished for this
proposed AD. As a matter of law, in order to be airworthy, an aircraft
must conform to its type design and be in a condition for safe
operation. The type design is approved only after the FAA makes a
determination that it complies with all applicable airworthiness
requirements. In adopting and maintaining those requirements, the FAA
has already made the determination that they establish a level of
safety that is cost-beneficial. When the FAA, as in this proposed AD,
makes a finding of an unsafe condition, this means that this cost-
beneficial level of safety is no longer being achieved and that the
proposed actions are necessary to restore that level of safety. Because
this level of safety has already been determined to be cost-beneficial,
a full cost-benefit analysis for this proposed AD would be redundant
and unnecessary.
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 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C.
106(g); and 14 CFR 11.89.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by removing amendment 39-8666 (58 FR
45044, August 26, 1993), and by adding a new airworthiness directive
(AD), to read as follows:
Boeing: Docket 94-NM-72-AD. Supersedes AD 93-16-09, Amendment 39-
8666.
Applicability: Model 757 series airplanes equipped with Pratt &
Whitney engines, 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 (f) 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.
Note 2: Inspections accomplished prior to the effective date of
this amendment in accordance with the procedures described in Boeing
Service Bulletin 757-54A0019, Revision 4, dated May 27, 1993;
Revision 3, dated March 26, 1992; or Revision 2, dated October 11,
1989; are considered acceptable for compliance with the applicable
inspection specified in this amendment.
To prevent cracking of the midspar fuse pins, which may lead to
separation of the strut and engine from the wing of the airplane,
accomplish the following:
(a) For airplanes equipped with straight fuse pins, part number
(P/N) 311N5067-1: Prior to the accumulation of 3,800 total flight
cycles on the straight fuse pin, perform an eddy current inspection
to detect cracking in the straight fuse pins, in accordance with
Boeing Service Bulletin 757-54A0019, Revision 5, dated March 17,
1994. [[Page 30211]]
(1) If no cracking is detected, repeat the inspection thereafter
at intervals not to exceed 1,000 flight cycles on the straight fuse
pin.
(2) If any cracking is detected, prior to further flight,
accomplish the requirements of either paragraph (a)(2)(i) or
(a)(2)(ii) of this AD.
(i) Replace the cracked straight fuse pin with a new straight
fuse pin, P/N 311N5067-1. Prior to the accumulation of 3,800 total
flight cycles on that newly installed straight fuse pin, perform an
eddy current inspection to detect cracking in that straight fuse
pin, in accordance with the service bulletin. Repeat the inspection
thereafter at intervals not to exceed 1,000 flight cycles on that
newly installed straight fuse pin. Or
(ii) Replace the cracked straight fuse pin with a new 15-5PH
fuse pin, P/N 311N5217-1. Prior to the accumulation of 14,000 total
flight cycles on that newly installed 15-5PH fuse pin, perform an
eddy current inspection to detect cracking in that newly installed
15-5PH fuse pin, in accordance with the procedures described in the
service bulletin. Repeat the inspection thereafter at intervals not
to exceed 3,500 flight cycles on that newly installed 15-5PH fuse
pin.
(b) For airplanes equipped with refinished straight fuse pins,
P/N 311N5067-1: Prior to the accumulation of 1,000 total flight
cycles on the refinished straight fuse pin, perform an eddy current
inspection to detect cracking in the refinished straight fuse pins,
in accordance with Boeing Service Bulletin 757-54A0019, Revision 5,
dated March 17, 1994.
(1) If no cracking is detected, repeat the inspection thereafter
at intervals not to exceed 1,000 flight cycles on the refinished
straight fuse pin.
(2) If any cracking is detected, prior to further flight,
accomplish the requirements of either paragraph (b)(2)(i),
(b)(2)(ii), or (b)(2)(iii) of this AD, in accordance with the
service bulletin.
(i) Replace the cracked refinished straight fuse pin with a
crack-free refinished straight fuse pin, P/N 311N5067-1. Prior to
the accumulation of 1,000 total flight cycles on that newly
installed refinished straight fuse pin, perform an eddy current
inspection to detect cracking in that newly installed refinished
straight fuse pin, in accordance with the procedures described in
the service bulletin. Repeat this inspection thereafter at intervals
not to exceed 1,000 flight cycles on the newly installed refinished
straight fuse pin. Or
(ii) Replace the cracked refinished straight fuse pin with a new
straight fuse pin, P/N 311N5067-1. Prior to the accumulation of
3,800 total flight cycles on that newly installed straight fuse pin,
perform an eddy current inspection to detect cracking in that newly
installed straight fuse pin, in accordance with the service
bulletin. Repeat the inspection thereafter at intervals not to
exceed 1,000 flight cycles on that newly installed straight fuse
pin. Or
(iii) Replace the cracked refinished straight fuse pin with a
new 15-5PH fuse pin, P/N 311N5217-1. Prior to the accumulation of
14,000 total flight cycles on that newly installed 15-5PH fuse pin,
perform an eddy current inspection to detect cracking in that newly
installed 15-5PH pin, in accordance with the procedures described in
the service bulletin. Repeat the inspection thereafter at intervals
not to exceed 3,500 flight cycles on that newly installed 15-5PH
fuse pin. -
(c) For airplanes equipped with bulkhead fuse pins, P/N
311N5211-1: Within 3,000 flight cycles after the effective date of
this AD, replace the bulkhead fuse pins with 15-5PH fuse pins, P/N
311N5217-1, in accordance with Boeing Service Bulletin 757-54A0019,
Revision 5, dated March 17, 1994, and accomplish the requirements of
paragraph (d) of this AD. -
(d) For airplanes equipped with 15-5PH fuse pins: Prior to the
accumulation of 14,000 total flight cycles on the 15-5PH fuse pins,
perform an eddy current inspection to detect cracking in those 15-
5PH fuse pins, in accordance with the procedures described in Boeing
Service Bulletin 757-54A0019, Revision 5, dated March 17, 1994. -
(1) If no cracking is detected, repeat the inspection thereafter
at intervals not to exceed 3,500 flight cycles on the 15-5PH fuse
pin. -
(2) If any cracking is detected, accomplish the requirements of
both paragraphs (d)(2)(i) and (d)(2)(ii) of this AD. -
(i) Prior to further flight, replace any cracked 15-5PH fuse pin
with a new 15-5PH fuse pin, P/N 311N5217-1, in accordance with the
procedures described in the service bulletin. And -
(ii) Prior to the accumulation of 14,000 total flight cycles on
that newly installed 15-5PH fuse pin, perform an eddy current
inspection to detect cracking in that newly installed 15-5PH fuse
pin, in accordance with the procedures described in the service
bulletin. Repeat the inspection thereafter at intervals not to
exceed 3,500 flight cycles on that newly installed 15-5PH fuse pin.
-
(e) Fuse pins must be of the same type on the same strut. For
example, a steel fuse pin having P/N 311N5067-1 may not be installed
on the same strut that has a corrosion-resistant steel (CRES) fuse
pin having P/N 311N5217-1 installed on that strut. However, fuse
pins on one strut may differ from those on another strut, provided
the fuse pins are not of mixed types on the same strut. -
(f) 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 3: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Seattle ACO.
-(g) 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 June 2, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 95-14055 Filed 6-7-95; 8:45 am]
BILLING CODE 4910-13-U
