03-22713. Airworthiness Directives; General Electric Aircraft Engines CT7 Series Turboprop Engines

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to supersede an existing airworthiness directive (AD) for certain General Electric Aircraft Engines (GEAE) CT7 series turboprop engines. That AD currently requires propeller gearbox (PGB) oil filter impending bypass button (IBB) inspections, oil filter inspections, replacement of left-hand and right-hand idler gears at time of PGB overhaul, and replacement of certain SN PGBs before accumulating 2,000 flight hours. This proposed AD would require the same actions, and adds additional SNs of affected PGBs. This proposed AD is prompted by reports of PGBs equipped with certain gears that do not meet design specifications, resulting in the same failure addressed in the existing AD. We are proposing this AD 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 auxiliary feathering system from fully feathering the propeller on certain PGBs.

DATES:

We must receive any comments on this proposed AD by November 7, 2003.

ADDRESSES:

Use one of the following addresses to submit comments on this proposed AD:

• By mail: 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.
• By fax: [phone].
• By e-mail: [e-mail].

You can get the service information identified in this proposed AD from General Electric Aircraft Engines, CT7 Series Turboprop Engines, 1000 Western Ave, Lynn, MA 01910; telephone [phone], fax [phone].

You may examine the AD docket at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA.

FOR FURTHER INFORMATION CONTACT:

Eugene Triozzi, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to submit any written relevant data, views, or arguments regarding this proposal. Send your comments to an address listed under ADDRESSES. Include “AD Docket No. 99-NE-48-AD” in the subject line of your comments. If you want us to acknowledge receipt of your mailed comments, send us a self-addressed, stamped postcard with the docket number written on it; we will date-stamp your postcard and mail it back to you. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. If a person contacts us verbally, and that contact relates to a substantive part of this proposed AD, we will summarize the contact and place the summary in the docket. We will consider all comments received by the closing date and may amend the proposed AD in light of those comments.

We are reviewing the writing style we currently use in regulatory documents. We are interested in your comments on whether the style of this document is clear, and your suggestions to improve the clarity of our communications that affect you. You may get more information about plain language at http://www.faa.gov/​language and http://www.plainlanguage.gov.

Examining the AD Docket

You may examine the AD Docket (including any comments and service information), by appointment, between 8 a.m. and 4:30 p.m., Monday through Friday, except Federal holidays. See ADDRESSES for the location.

Discussion

On March 12, 2003, the FAA issued AD 2003-06-03 (Amendment 39-13090, 68 FR 13618, March 20, 2003). That AD requires initial and repetitive inspections of the PGB oil filter IBB for extension (popping), and follow-on inspections, maintenance, and replacement actions if the PGB oil filter IBB is popped, and if necessary, replacement of the PGB with a serviceable PGB. In addition, that amendment requires replacement of certain left-hand and right-hand idler gears at time of overhaul of PGBs, and the replacement of certain SN PGBs before accumulating 2,000 flight hours. That AD was 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. That condition, if not corrected, could result in uncontained PGB failure and internal bulkhead damage, possibly prohibiting the auxiliary feathering system from fully feathering the propeller on certain PGBs.

Actions Since AD 2003-06-03 was Issued

Since that AD was issued, the FAA has learned that a certain population of PGBs have been discovered equipped with certain gears that do no meet design specifications. This can result in the same PGB failure described in AD 2003-06-03.

Relevant Service Information

For AD 2003-06-03, the FAA previously reviewed and approved the technical contents of:

• GEAE CT7 Turboprop Service Bulletin (SB) CT7-TP S/B 72-0453, dated July 27, 2001, that describes procedures for inspections of the PGB oil filter IBB for extension, and if the oil filter IBB is extended, follow-on inspections, maintenance, and replacement actions. This SB also identifies PGBs by SN that require inspection; and
• GEAE CT7 Turboprop SB CT7-TP S/B 72-0452, dated July 27, 2001, that requires replacement of certain SNs of left-hand and right-hand idler gears with serviceable gears. This SB also identifies affected PGBs by SN.
• For this proposal, the FAA has reviewed and approved the technical contents of GEAE CT7 Turboprop Alert Service Bulletin CT7-TP S/B 72-A0466, dated April 17, 2003, that lists the population of SNs of PGBs susceptible to gears not meeting design specifications.

FAA's Determination and Requirements of the Proposed AD

We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other products of this same type design. Therefore, we are proposing this AD, which would require:

• Initial and repetitive inspections of the propeller gearbox (PGB) oil filter IBB for extension (popping).
• Follow-on inspections, maintenance, and replacement actions if the PGB oil filter IBB is popped, and if necessary, replacement of the PGB with a serviceable PGB.
• Replacement of certain left-hand and right-hand idler gears at time of overhaul of PGBs, and the replacement of certain SN PGBs before accumulating 2,000 flight hours after April 24, 2003, the effective date of AD 2003-06-03.

The proposed AD would require that you do these actions using the service information described previously.

Changes to 14 CFR Part 39—Effect on the Proposed AD

On July 10, 2002, we published a new version of 14 CFR part 39 (67 FR 47997, July 22, 2002), which governs the FAA's AD system. This regulation now includes material that relates to altered products, special flight permits, and alternative methods of compliance. This material previously was included in each individual AD. Since this material is included in 14 CFR part 39, we will not include it in future AD actions.

Costs of Compliance

There are about 667 GEAE CT7 series turboprop engines of the affected design in the worldwide fleet. We estimate that 400 engines installed on airplanes of U.S. registry would be affected by this proposed AD. We also estimate that each IBB inspection would take approximately 0.25 work hours per engine, and the average labor rate is $65 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. Therefore, the total cost on U.S. operators would be approximately $56,378,500.

Regulatory Findings

We have determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD 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.

For the reasons discussed above, I certify that the 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. Would not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.

We prepared a summary of the costs to comply with this proposal and placed it in the AD Docket. You may get a copy of this summary by sending a request to us at the address listed under ADDRESSES. Include “AD Docket No. 99-NE-48-AD” in your request.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 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.

§ 39.13

[Amended]

2. The FAA amends § 39.13 by removing Amendment 13090, 68 FR 13618, March 20, 2003, and by adding a new airworthiness directive, Amendment 39-XXXXX, to read as follows:

General Electric Aircraft Engines: Docket No. 99-NE-48-AD. Supersedes AD 2003-06-03, Amendment 39-13090.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this airworthiness directive (AD) action by November 7, 2003.

Affected ADs

(b) This AD supersedes AD 2003-06-03, Amendment 39-13090.

Applicability

(c) This AD applies to General Electric Aircraft Engines (GEAE) CT7 series turboprop engines, with propeller gearboxes (PGBs) identified by serial number (SN) in Table 1 of GEAE CT7 Turboprop Service Bulletin (SB) CT7-TP S/B 72-0452, dated July 27, 2001, and Table 1 of GEAE CT7 Turboprop Alert Service Bulletin (ASB) CT7-TP S/B 72-A0466, dated April 17, 2003. These engines are installed on but not limited to SAAB 340 series airplanes.

Unsafe Condition

(d) This AD is prompted by reports of additional PGBs equipped with certain gears that do not meet design specifications, resulting in the same failure addressed in the AD being superseded. We are issuing this AD 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 auxiliary feathering system from fully feathering the propeller on certain PGBs.

Compliance

(e) You are responsible for having the actions required by this AD performed within the compliance times specified unless the actions have already been done.

(f) Inspect the PGB oil filter impending bypass button (IBB) for extension using 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.

(g) If the PGB oil filter IBB is extended, replace the oil filter and perform follow-on inspections, using paragraph 3.A of the Accomplishment Instructions of GEAE CT7 Turboprop SB CT7-TP S/B 72-0453, dated July 27, 2001.

(h) 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. Use the Accomplishment Instructions of GEAE CT7 Turboprop SB CT7-TP S/B 72-0452, dated July 27, 2001 to replace the gears.

(i) 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 SB CT7-TP S/B 72-0452, dated July 27, 2001, replace the PGB before accumulating an additional 2,000 engine flight hours after April 24, 2003, the effective date of AD 2003-06-03.

Terminating Action

(j) Replacement of left-hand and right-hand idler gears in accordance with paragraph (h) of this AD, or replacement of the PGB in accordance with paragraph (i) of this AD constitutes terminating action to the repetitive inspections required by paragraph (f) of this AD.

Alternative Methods of Compliance

(k) The Manager, Engine Certification Office, has the authority to approve alternative methods of compliance for this AD if requested using the procedures found in 14 CFR 39.19.

Special Flight Permits

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

Material Incorporated by Reference

(m) You must use the service information specified in Table 1 to perform the inspections and replacements required by this AD. Approval of incorporation by reference from the Office of the Federal Register is pending for GEAE CT7 Turboprop ASB CT7-TP S/B 72-A0466, dated April 17, 2003. Table 1 follows:

Table 1.—Incorporation by Reference

Service bulletin no.	Page	Revision	Date
SB CT7-TP S/B 72-0452	ALL	Original	July 27, 2001.
Total Pages: 12
SB CT7-TP S/B 72-0453	ALL	Original	July 27, 2001.
Total Pages: 5
ASB CT7-TP S/B 72-A0466	ALL	Original	April 17, 2003.
Total Pages: 8

Related Information

(n) None.

Issued in Burlington, Massachusetts, on September 2, 2003.

Jay J. Pardee,

Manager, Engine and Propeller Directorate, Aircraft Certification Service.