[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