[Federal Register Volume 60, Number 96 (Thursday, May 18, 1995)]
[Proposed Rules]
[Pages 26696-26700]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-12207]
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[[Page 26697]]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 94-NM-71-AD]
Airworthiness Directives; Boeing Model 757 Series Airplanes
Equipped with Rolls Royce 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
requirements 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 9, 1995.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 94-NM-71-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-71-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-71-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 40488). That NPRM would have superseded AD 93-16-08, amendment
39-8665 (58 FR 45041, August 26, 1993), to require inspection of
straight fuse pins, replacement of cracked straight fuse pins with
either new 15-5PH corrosion-resistant steel fuse pins or like pins,
replacement of bulkhead fuse pins with new 15-5PH corrosion-resistant
steel fuse pins, and repetitive inspections of newly installed fuse
pins. Installation of the new 15-5PH corrosion-resistant steel fuse
pins would allow a longer interval for repetitive inspection than was
previously provided by AD 93-16-08. 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.
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Due consideration has been given to
the comments received.
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 93-16-08 to inspect repetitively currently installed
refinished straight fuse pins. However, this requirement was
inadvertently excluded; therefore, a new paragraph (b) has been added
to this supplemental NPRM.
[All paragraphs subsequent to paragraph (b) have been redesignated
in this supplemental NPRM to accommodate the new paragraph (b); see
discussion, above.]
One commenter requests that the proposed requirement in paragraph
(b) to replace 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. Finally, the
commenter points out that the proposed 90-day compliance time is
inconsistent with that of a similar AD that requires inspections/
replacement of the bulkhead fuse pins on Model 747 series airplanes.
The FAA concurs. The FAA has reviewed the test data submitted by
this commenter and has determined that extending the compliance time of
paragraph (c) of the supplemental NPRM to 3,000 flight cycles will not
[[Page 26698]] adversely affect safety. The FAA finds that 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.
Since issuance of the proposal, the FAA has found that the proposed
repetitive inspection interval of 3,000 flight cycles for inspection of
the new 15-5PH fuse pins may not coincide with operators' regularly
scheduled maintenance visits. The FAA finds that extending the
compliance time by 500 additional 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 notice have been revised to specify a repetitive
inspection interval of 3,500 flight cycles for inspection of the new
15-5PH corrosion-resistant steel fuse pins. Additionally, the newly
added paragraph (b)(2)(iii) of this supplemental NPRM, specifies a
repetitive interval of 3,500 flight cycles for inspection of refinished
straight fuse pins. [Paragraph (c) of the proposal has been
redesignated as paragraph (d) of this supplemental NPRM; see
discussion, above.]
Further, since issuance of the proposal, the FAA has found that
Boeing Service Bulletin 757-54A0020, 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.
However, that service bulletin does describe eddy current inspection
procedures for the old style fuse pins, part number 311N5067-1, and the
FAA finds that these procedures are also applicable to the new 15-5PH
fuse pins. Therefore, paragraphs (a)(2)(ii), (b)(2)(iii), and
(d)(2)(ii) of this supplemental NPRM have been revised to 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 reviewed and reconsidered the replacement requirements
that were proposed in the original NPRM. The FAA finds that confusion
may exist concerning whether straight fuse pins may be replaced
independently of the other fuse pin on the same strut when only one
fuse pin is cracked. 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
double shear load of the fuse pin 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 notice to clarify the proposed replacement requirement.
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 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 306 Model 757 series airplanes equipped
with Rolls Royce engines of the affected design in the worldwide fleet.
The FAA estimates that 119 airplanes of U.S. registry would be affected
by this proposed AD.
The inspections that were previously required by AD 93-16-08, and
retained in this supplemental proposal take approximately 8 work hours
per fuse pin at an average labor rate is $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 $228,480, 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 93-16-08.
The proposed replacement would take approximately 56 work hours per
fuse pin at an average labor rate of $60 per work hour. 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 $1,599,360, or $13,440 per airplane.
The total 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 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 [[Page 26699]] 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 39-8665 (58 FR
45041, August 26, 1993), and by adding a new airworthiness directive
(AD), to read as follows:
Boeing: Docket 94-NM-71-AD. Supersedes AD 93-16-08, Amendment 39-
8665.
Applicability: Model 757 series airplanes equipped with Rolls
Royce 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) 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 757-54A0020, Revision 4, dated May 27, 1993;
Revision 3, dated March 26, 1992; or Revision 2, dated October 31,
1991; 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 5,000 total flight
cycles on the straight fuse pin, perform an eddy current inspection
to detect cracking in those fuse pins, in accordance with Boeing
Service Bulletin 757-54A0020, Revision 5, dated March 17, 1994.
(1) If no cracking is detected, repeat the inspection thereafter
at intervals not to exceed 1,500 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, and prior to the accumulation of 5,000
total flight cycles on the newly installed straight fuse pin,
perform an eddy current inspection, in accordance with the service
bulletin. Repeat the inspection thereafter at intervals not to
exceed 1,500 flight cycles on the newly installed straight fuse pin.
Or
(ii) Replace the cracked straight fuse pin with a new 15-5PH
fuse pin, P/N 311N5217-1, and prior to the accumulation of 14,000
total flight cycles on the newly installed 15-5PH fuse pin, perform
an eddy current inspection to detect cracking in the newly installed
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 the newly installed fuse pin.
(b) For airplanes equipped with refinished straight fuse pins,
P/N 311N5067-1: Perform an eddy current inspection to detect
cracking in those fuse pins at intervals not to exceed 1,500 flight
cycles on the refinished fuse pins, in accordance with Boeing
Service Bulletin 757-54A0020, Revision 5, dated March 17, 1994.
(1) If no cracking is detected, repeat the inspection thereafter
at intervals not to exceed 1,500 flight cycles on the refinished
straight fuse pin.
(2) If any cracking is detected, prior to further flight,
accomplish the requirements of 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, and perform
an eddy current inspection to detect cracking in the refinished
straight fuse pin at intervals not to exceed 1,500 flight cycles, in
accordance with the procedures described in the service bulletin. Or
(ii) Replace the cracked refinished straight fuse pin with a new
straight fuse pin, P/N 311N5067-1, and prior to the accumulation of
5,000 total flight cycles on the newly installed straight fuse pin,
perform an eddy current inspection, in accordance with the service
bulletin. Repeat the inspection thereafter at intervals not to
exceed 1,500 flight cycles on the 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, and prior to the accumulation
of 14,000 total flight cycles on the newly installed 15-5PH fuse
pin, perform an eddy current inspection to detect cracking in the
newly installed 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 the newly installed 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 757-54A0020,
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 fuse
pins, in accordance with the procedures described in Boeing Service
Bulletin 757-54A0020, 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 fuse pin.
(2) If any cracking is detected, accomplish the requirements of
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
the newly installed 15-5PH fuse pin, perform an eddy current
inspection to detect cracking in the newly installed 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 the newly installed fuse pin.
(e) Fuse pins must be of the same type on the same strut. For
example, a steel fuse pin [[Page 26700]] 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
Secs. 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 May 12, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 95-12207 Filed 5-17-95; 8:45 am]
BILLING CODE 4910-13-U
