E8-18811. Airworthiness Directives; Pratt & Whitney (P&W) PW4000 Series 94-Inch Fan Turbofan Engines

AGENCY:

Federal Aviation Administration (FAA), Department of Transportation (DOT).

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for P&W PW4052, PW4056, PW4060, PW4062, PW4152, PW4156A, PW4158, PW4460, and PW4462 turbofan engines. This proposed AD would require a onetime visual inspection of all EEC-131 model electronic engine controls (EECs). This proposed AD would require the EECs to be identified, categorized by group number, marked, and replaced using a fleet management plan. This proposed AD results from a report of an uncommanded engine in-flight shutdown due to defective EEC pulse width modulator (PWM) microcircuits. We are proposing this AD to prevent uncommanded in-flight engine shutdowns which could result in loss of thrust and prevent continued safe flight or landing.

DATES:

We must receive any comments on this proposed AD by September 15, 2008.

ADDRESSES:

Use one of the following addresses to comment on this proposed AD.

• Federal eRulemaking Portal: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
• Mail: Docket Management Facility, U.S. Department of Transportation, 1200 New Jersey Avenue, SE., West Building Ground Floor, Room W12-140, Washington, DC 20590-0001.
• Hand Delivery: Deliver to Mail address above between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.
• Fax: [phone].

You can get the service information identified in this proposed AD from Pratt & Whitney, 400 Main St., East Hartford, CT 06108; telephone [phone]; fax [phone].

FOR FURTHER INFORMATION CONTACT:

V. Rose Len, Aerospace Engineer, Engine Certification Office, FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; e-mail: [e-mail]; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send us any written relevant data, views, or arguments regarding this proposal. Send your comments to an address listed under ADDRESSES. Include “Docket No. FAA-2008-0589; Directorate Identifier 2008-NE-17-AD” in the subject line of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments received by the closing date and may amend the proposed AD in light of those comments.

We will post all comments we receive, without change, to http://www.regulations.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this proposed AD. Using the search function of the Web site, anyone can find and read the comments in any of our dockets, including, if provided, the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78).

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.gov; or in person at the Docket Operations office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this proposed AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Operations office (telephone [phone]) is the same as the Mail address provided in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

Discussion

In May of 2006 we received a report of an uncommanded engine in-flight shutdown of a P&W PW4152 turbofan engine. The investigation of this event determined that certain EECs were built with defective PWM microcircuits. The defective microcircuits degrade over time as a result of thermal cycling while operating within their certified temperature range. In operation, the EEC system tests the functional capability of the PWM in Channel A. If the Channel A PWM fails the test, the EEC automatically switches to the Channel B PWM. In this case, both of the EEC PWMs are degrading similarly and the Channel B PWM is also likely to fail, at which time the EEC automatically shuts down the engine. Based on a risk analysis provided by P&W which we reviewed and concurred, this condition, if not corrected, could result in uncommanded in-flight engine shutdowns, which could result in loss of thrust and prevent continued safe flight or landing.

The defective PWMs are the result of a change from the original PWM design introduced by a single microcircuit supplier before 1993. Our investigation showed that the supplier returned to the original PWM design between 1993 and 1994. The EEC supplier determined the population of affected EECs by testing model EEC-131 EECs built after the introduction of the PWM design change. The EEC supplier performed destructive testing of the PWMs, and identified four distinct groups of EECs by serial number:

Group 1: EECs with a high concentration of PWMs that failed during testing.

Group 2: EECs with a low concentration of PWMs that failed during testing.

Group 3: All EECs not in Group 1 or Group 2 but may contain suspect PWMs due to board swapping during the repair or refurbishment of the EEC.

Group 4: EECs have been inspected for defective PWMs and repaired if required.

To facilitate the timely removal of the defective PWMs from the fleet, all of the EECs must first be identified, categorized, and marked by their group number so that the higher risk EECs will be replaced before the lower risk EECs are replaced. Group 4 EECs have been inspected or repaired, so they are not subject to the same PWM problem. However, they still require further internal and external labeling for tracking purposes. Labeling will be done using P&W Alert Service Bulletin (ASB) No. PW4ENG 73-216, dated April 8, 2008.

Relevant Service Information

We have reviewed and approved the technical contents of P&W ASB No. PW4ENG A73-214, Revision 2, dated May 23, 2008. That ASB describes procedures for inspecting, identifying, categorizing, and marking all EEC-131 model EECs that are identified by part number and serial number into four groups. The Group 1 EECs have a high probability of having defective PWM microcircuits, while the other groups have a lower probability of having defective PWM microcircuits.

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. We are proposing this AD, which would require a onetime visual inspection of all EEC-131 model EECs. The proposed AD would also require the EECs to be identified, categorized by group number, marked, and replaced using a fleet management plan. The proposed AD would require you to use the service information described previously to perform these actions.

Costs of Compliance

We estimate that this proposed AD would affect 730 P&W PW4000 series 94-inch fan turbofan engines installed on airplanes of U.S. registry. We also estimate that it would take about 1 work-hour per engine to inspect, categorize, and mark each of the 730 EECs, and 1 work-hour per engine to replace up to 730 EECs. The average labor rate is $80 per work-hour. Required replacement parts would cost about $400 per engine. Based on these figures, we estimate the total cost of the proposed AD to U.S. operators to be $467,200.

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, Section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency's authority.

We are issuing this rulemaking under the authority described in subtitle VII, part A, subpart III, section 44701, “General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

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 AD:

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 regulatory evaluation of the estimated costs to comply with this proposed AD. You may get a copy of this summary at the address listed under ADDRESSES.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

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 adding the following new airworthiness directive:

Pratt & Whitney: Docket No. FAA-2008-0589; Directorate Identifier 2008-NE-17-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this airworthiness directive (AD) action by September 15, 2008.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Pratt & Whitney (P&W) PW4052, PW4056, PW4060, PW4062, PW4152, PW4156A, PW4158, PW4460, and PW4462 turbofan engines. These engines are installed on, but not limited to, Airbus A300-600 and A310-300, and Boeing 747-400, Boeing 767-200, 767-300, and MD-11 series airplanes.

Unsafe Condition

(d) This AD results from a report of an uncommanded engine in-flight shutdown due to defective electronic engine control (EEC) pulse width modulator (PWM) microcircuits. We are issuing this AD to prevent uncommanded in-flight engine shutdowns which could result in loss of thrust and prevent continued safe flight or landing.

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.

Onetime Visual Inspection and Reporting Requirements

(f) Within 600 operating hours after the effective date of this AD:

(1) Perform a onetime visual inspection of the EEC-131 model EECs to identify, categorize, and mark them as a Group 1, Group 2, Group 3, or Group 4 EEC.

(2) Use paragraphs 1 through 7 in the Accomplishment Instructions of P&W Alert Service Bulletin No. PW4ENG A73-214, Revision 2, dated May 23, 2008, to inspect, categorize, and mark the EECs.

(3) Within 30 calendar days of completing paragraph (f)(1) of this AD, report all inspection findings to V. Rose Len, Engine Certification Office, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803.

(4) The Office of Management and Budget (OMB) has approved the reporting requirements and assigned OMB control number 2120-0056.

Replacement of Group 1 EECs

(g) Replace Group 1 EECs with a serviceable EEC before reaching 2,000 cycles-in-service (CIS) since new, but not later than one year from the effective date of this AD.

Replacement of Groups 2, 3, and 4 EECs

(h) Replace the following groups of EECs with a serviceable EEC, or any EEC that does not violate the EEC installation procedure as provided by paragraphs (k), (l), and (m) of this AD, as follows:

(1) Group 2 EECs, before reaching 4,000 CIS since new, but not later than 2 years after the effective date of this AD.

(2) Group 3 EECs, before reaching 14,000 CIS since new, but not later than 6 years after the effective date of this AD.

Definition of Serviceable EECs

(i) A serviceable EEC is an EEC that does not violate the EEC installation procedure as provided by paragraphs (k), (l), and (m) of this AD, or is marked as Group 4 per P&W ASB No. PW4ENG 73-214, Revision 2, dated May 23, 2008, or has been repaired per P&W Service Bulletin (SB) No. PW4ENG 73-216, dated April 8, 2008. Once an EEC has been repaired, it is viewed as a Group 4 EEC.

(j) Information on obtaining a serviceable EEC can be found in P&W SB No. PW4ENG 73-216, dated April 8, 2008.

EEC Installation Prohibition

(k) Do not install any Group 1 EEC after 1 year from the effective date of this AD or any Group 1 EEC that has reached 2,000 CIS since new.

(l) Do not install any Group 2 EEC after 2 years from the effective date of this AD or any Group 2 EEC that has reached 4,000 CIS since new.

(m) Do not install any Group 3 EEC after 6 years from the effective date of this AD or any Group 3 EEC that has reached 14,000 CIS since new.

Alternative Methods of Compliance

(n) 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.

Related Information

(o) Contact V. Rose Len, Aerospace Engineer, Engine Certification Office, FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; e-mail: [e-mail]; telephone [phone]; fax [phone], for more information about this AD.

Issued in Burlington, Massachusetts, on August 8, 2008.

Peter A. White,

Assistant Manager, Engine and Propeller Directorate, Aircraft Certification Service.