[Federal Register Volume 67, Number 114 (Thursday, June 13, 2002)]
[Proposed Rules]
[Pages 40623-40625]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-14857]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NE-48-AD]
RIN 2120-AA64


Airworthiness Directives; General Electric Aircraft Engines CT7 
Series Turboprop Engines

AGENCY: Federal Aviation Administration, DOT.

[[Page 40624]]


ACTION: Supplemental notice of proposed rulemaking (NPRM).

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SUMMARY: This action revises an earlier proposed airworthiness 
directive (AD), applicable to certain General Electric Aircraft Engines 
(GEAE) CT7 series turboprop engines, that would have required initial 
and repetitive inspections and replacement of possibly improperly 
hardened PGB input pinions for certain serial number (SN) propeller 
gearboxes (PGB's). This action revises the proposed rule by eliminating 
the requirement for a one-time removal of possibly improperly hardened 
PGB input pinions, proposes a requirement to replace certain left-hand 
and right-hand idler gears at time of overhaul of PGB's, and proposes 
the replacement of certain SN PGB's before accumulating 2,000 flight 
hours. This proposal is prompted by an on-going investigation that 
concluded that low-time PGB removals are due to accelerated wear of the 
PGB idler gears, rather than improperly hardened PGB input pinions. The 
actions specified by the proposed AD are intended to prevent separation 
of PGB left-hand and right-hand idler gears, which could result in 
uncontained PGB failure and internal bulkhead damage, possibly 
prohibiting the auxilliary feathering system from fully feathering the 
propeller on certain PGB's.

DATES: Comments must be received by August 12, 2002.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), New England Region, Office of the Regional 
Counsel, Attention: Rules Docket No. 99-NE-48-AD, 12 New England 
Executive Park, Burlington, MA 01803-5299. Comments may be inspected at 
this location, by appointment, between 8 a.m. and 4:30 p.m., Monday 
through Friday, except Federal holidays. Comments may also be sent via 
the Internet using the following address: ``[email protected]''. 
Comments sent via the Internet must contain the docket number in the 
subject line.
    The service information referenced in the proposed rule may be 
obtained from General Electric Aircraft Engines CT7 Series Turboprop 
Engines, 1000 Western Ave, Lynn, MA 01910; telephone (781) 594-3140, 
fax (781) 594-4805. This information may be examined, by appointment, 
at the FAA, New England Region, Office of the Regional Counsel, 12 New 
England Executive Park, Burlington, MA.

FOR FURTHER INFORMATION CONTACT: Barbara Caufield, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park; telephone (781) 238-7146, fax (781) 238-
7199.

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 should 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 action 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 action must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 99-NE-48-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRM's

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, New England Region, Office of the Regional Counsel, 
Attention: Rules Docket No. 99-NE-48-AD, 12 New England Executive Park, 
Burlington, MA 01803-5299.

Discussion

    A proposal to amend part 39 of the Federal Aviation Regulations (14 
CFR part 39) to add an AD, applicable to General Electric Aircraft 
Engines (GEAE) CT7 series turboprop engines, was published as a notice 
of proposed rulemaking (NPRM) in the Federal Register on May 4, 2000 
(65 FR 25892). That NPRM proposed initial and repetitive inspections of 
the PGB oil filter impending bypass button (IBB) for extension.
    If the PGB oil filter IBB was extended, the proposed AD would have 
required follow-on inspections, maintenance, and if necessary, 
replacement of the PGB with a serviceable PGB. In addition, that 
proposed AD would have required, at the next return of the PGB to a CT7 
turboprop overhaul facility after the effective date of the proposed 
AD, replacing possibly improperly hardened PGB input pinions with PGB 
input pinions manufactured with the proper hardening process. That 
proposed AD was prompted by reports of improperly hardened propeller 
gearbox (PGB) input pinions installed on General Electric Aircraft 
Engines (GEAE) CT7 series turboprop engines.
    Since the issuance of that proposed AD, the FAA has determined that 
low-time PGB removals are not related to improperly hardened PGB input 
pinions. Analyses by the manufacturer and fleet operating experience 
have shown that improperly hardened PGB input pinions do not create an 
unsafe condition. It has been determined that low-time PGB removals are 
caused by accelerated wear of the PGB idler gears. The accelerated wear 
is caused by nonconforming gear surface conditions, which subject the 
gears to premature distress. This condition has been linked to the 
original manufacturer of a specific population of PGB gears. This 
condition, if not corrected, could result in separation of PGB left-
hand and right-hand idler gears, which could result in uncontained PGB 
failure. For PGB's that are mated to Hamilton Standard propellers, 
separation of an idler gear that results in PGB internal bulkhead 
damage could possibly prohibit the auxilliary feathering system from 
fully feathering the propeller.
    Since this change expands 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.

Manufacturer's Service Bulletins (SB's)

    The FAA has reviewed and approved the technical contents of GEAE 
CT7 Turboprop Service Bulletin CT7-TP S/B 72-0453, dated July 27, 2001, 
that describes procedures for inspections of the PGB oil filter 
impending bypass button (IBB) for extension, and if the oil filter IBB 
is extended, follow-on inspections, maintenance, and replacement 
actions. This SB also identifies PGB's by SN that require inspection. 
The FAA has also reviewed and approved the technical contents of GEAE 
CT7 Turboprop Service Bulletin CT7-TP S/B 72-0452, dated July 27, 2001, 
that requires replacement of certain SN's of left-hand and right-hand 
idler gears with serviceable gears. This SB also identifies affected 
PGB's by SN.

[[Page 40625]]

FAA's Determination of an Unsafe Condition and Proposed Actions

    Since an unsafe condition has been identified that is likely to 
exist or develop on other GEAE CT7 series turboprop engines of the same 
type design, the proposed AD would require:
     Initial inspection of the PGB oil filter IBB for extension 
within 50 hours time-in-service (TIS) after the effective date of this 
AD and,
     If the PGB oil filter IBB is extended, follow-on 
inspections, maintenance, and replacement actions.
     Repetitive inspections of the PGB oil filter IBB before 
the first flight of each operational day.
     Replacing certain left-hand and right-hand idler gears 
with serviceable gears at the next return of the PGB to a CT7 turboprop 
overhaul facility.
     Replacing certain PGB's that are mated to a Hamilton 
Standard propeller before accumulating 2,000 engine flight hours.
    Since this change expands 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.

Economic Analysis

    There are approximately 150 engines of the affected design 
installed on airplanes of US registry that would be affected by this 
proposed AD. The FAA estimates that each IBB inspection would take 
approximately 0.25 work hours per engine, and the average labor rate is 
$60 per work hour. Inspection and replacement of idler gears would take 
approximately four work hours per engine at time of PGB overhaul. 
Replacement cost for idler gears per PGB is estimated to be $140,670. 
Replacement of a PGB would take approximately 48 hours. Therefore, the 
total cost on US operators would be approximately $21,138,750.

Regulatory Analysis

    This proposed rule does not have federalism implications, as 
defined in Executive Order 13132, because it would not have a 
substantial direct effect 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. 
Accordingly, the FAA has not consulted with state authorities prior to 
publication of this proposed rule.
    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. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

General Electric Aircraft Engines: Docket No. 99-NE-48-AD.

Applicability

    General Electric Aircraft Engines (GEAE) CT7 series turboprop 
engines, with propeller gearboxes (PGB's) identified by serial 
number (SN) in Table 1 of GEAE CT7 Turboprop Service Bulletin CT7-TP 
S/B 72-0452, dated July 27, 2001. These engines are installed on but 
not limited to SAAB 340 series airplanes.

    Note 1: This AD applies to each engine 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 engines that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (f) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

Compliance

    Compliance with this AD is required as indicated, unless already 
done.
    To prevent separation of PGB left-hand and right-hand idler 
gears, which could result in uncontained PGB failure and internal 
bulkhead damage, possibly prohibiting the auxilliary feathering 
system from fully feathering the propeller on certain PGB's, do the 
following:
    (a) Inspect the PGB oil filter impending bypass button (IBB) for 
extension in accordance with the following schedule:
    (1) Initially inspect within 50 hours time-in-service (TIS) 
after the effective date of this AD.
    (2) Thereafter, inspect each operational day.
    (b) If the PGB oil filter IBB is extended, replace the oil 
filter and perform follow-on inspections in accordance with 3.A of 
the Accomplishment Instructions of GEAE CT7 Turboprop Service 
Bulletin CT7-TP S/B 72-0453, dated July 27, 2001.
    (c) At the next return of the PGB to a CT7 turboprop overhaul 
facility after the effective date of this AD, replace left-hand and 
right-hand idler gears in accordance with the Accomplishment 
Instructions of GEAE CT7 Turboprop Service Bulletin CT7-TP S/B 72-
0452, dated July 27, 2001.
    (d) If the PGB is mated to a Hamilton Standard propeller and the 
left-hand and right-hand idler gears have not been replaced in 
accordance with the Accomplishment Instructions of GEAE CT7 
Turboprop Service Bulletin CT7-TP S/B 72-0452, dated July 27, 2001, 
replace the PGB before accumulating an additional 2,000 engine 
flight hours after the effective date of this AD.

Terminating Action

    (e) Replacement of left-hand and right-hand idler gears in 
accordance with paragraph (c) of this AD, or replacement of the PGB 
in accordance with paragraph (d) of this AD constitutes terminating 
action to the repetitive inspections required by paragraph (a) of 
this AD.

Alternative Method of Compliance

    (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, Engine Certification Office (ECO). 
Operators must submit their request through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, ECO.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this airworthiness directive, 
if any, may be obtained from the ECO.

Special Flight Permits

    (g) Special flight permits may be issued only for an airplane 
that has not more than one engine with a PGB oil filter IBB 
extended, to operate the airplane to a location where the 
requirements of this AD can be done.

    Issued in Burlington, Massachusetts, on June 4, 2002.
Francis A. Favara,
 Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 02-14857 Filed 6-12-02; 8:45 am]
BILLING CODE 4910-13-P