AD 2000-22-01

Effective November 9, 2000.

Comments for inclusion in the Rules Docket must be received on or before December 26, 2000.

Submit comments in triplicate to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 2000-NE-47-AD, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may also be sent via the Internet using the following address: “9-ane-adcomment@faa.gov.” Comments sent via the Internet must contain the docket number in the subject line.

The docket file for this AD may be examined at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA.

Peter White, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-7128, fax (781) 238-7199.

The FAA has been informed of nine surge events on PW4000 series engines that incorporate the HPC CBS configuration and that are used on Boeing 747, Boeing 767, and McDonnell Douglas MD-11 series airplanes. The surges were as follows:

• two occurred during takeoff,

• two occurred during climb,

• four occurred during ground testing,

• one occurred in a test cell shortly after selecting takeoff power.

The FAA issued AD 99-17-16, Amendment 39-11263 on August 12, 1999 (64 FR 45426, August 20, 1999). That AD requires short-term criteria for limiting the number of engines with potentially reduced stability on each airplane to no more than one engine, requires initial and repetitive on-wing or test cell cold-engine HPC stability tests, requires removal of engines from service that fail on-wing test acceptance criteria, and allows a follow-on test cell stability test. AD 99-17-16 also establishes required intervals for stability testing of the remaining engine with potentially reduced stability on the airplane and requirements for reporting test data. That amendment was prompted by a report of a dual-engine HPC surge event and reports of single-engine HPC surge events during the takeoff and climb phases of flight.

Subsequent to that AD, PW introduced a new design and full authority digital electronic control (FADEC) logic changes to address the problem of HPC rear stage surges. After the two latest surge events that occurred during takeoff, PW's preliminary analysis indicates that these events originated in the front stages of the HPC. A Weibull analysis conducted by PW revealed that the takeoff surge rate on engines with the HPC CBS configuration is about 11 times higher than the historical takeoff surge of the HPC non-CBS configuration. This condition, if not corrected, could result in a multiple-engine power loss due to HPC surges, which could result in engine power loss at a critical phase of flight such as takeoff or climb. The investigation is on-going and we may take further rulemaking action. We have coordinated with the Transport Airplane Directorate, the office responsible for certificating the airplanes on which the engines are installed.

The stability testing defined in AD 99-17-16 is ineffective in evaluating the stability of the HPC CBS configuration, because those tests assess rear stage HPC stability and not front stage HPC stability, which is limiting for the HPC CBS configuration engines. The FAA has issued alternative methods of compliance (AMOC's) to PW intended for use by all operators for certain HPC CBS configuration engines exempting them from the initial and repetitive testing requirements of AD 99-17-16. These AMOC's are not affected by this AD.

Since an unsafe condition has been identified that is likely to exist or develop on other PW4000 series turbofan engines of the same type design, this AD is being issued to prevent a multiple-engine power loss due to HPC surges, which could result in engine power loss at a critical phase of flight, such as takeoff or climb. This AD requires limiting the number of engines with the HPC CBS configuration installed, and that are used on Boeing 747, Boeing 767, and McDonnell Douglas MD-11 series airplanes, to one on each airplane according to the cyclic limits specified in this AD. This AD also prohibits using engines with HPC modules that incorporated PW service bulletin (SB) PW4ENG 72-706, Revision No. 3, dated July 17, 2000, or earlier revision, or SB PW4ENG 72-711, dated June 13, 2000, after the effective date of this AD.

Since a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.

Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the 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 that summarizes each FAA-public contact concerned with the substance of this AD 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 No. 2000-NE-47-AD.” The postcard will be date stamped and returned to the commenter.

This 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 rule.

The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and is not a “significant regulatory action” under Executive Order 12866.

It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, may be obtained from the Rules Docket at the location provided under the caption ADDRESSES.

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:

1. The authority citation for part 39 continues to read as follows:

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