Airworthiness Directives; Rolls-Royce plc RB211-535 Series Turbofan Engines

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Final rule.

SUMMARY:

This amendment adopts a new airworthiness directive (AD) that is applicable to Rolls-Royce plc RB211-535 series turbofan engines. This AD will require removal from service of suspect radial drive steady bearings with certain serial number prefixes and replacement with serviceable parts. This amendment was prompted by reports of a number of radial drive steady bearing failures from distinct batches of parts. The actions specified by this AD are intended to prevent radial drive steady bearing failure, which could result in an in-flight engine shutdown and smoke and fumes in the cabin.

DATES:

Effective date July 11, 2000.

ADDRESSES:

The service information referenced in this AD may be obtained from Rolls-Royce plc, P.O. Box 31, Derby, DE24 8BJ, UK; telephone 011-44-1332-242424. This information may be examined at the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA, or at the Office of the Federal Register, 800 North Capitol Street, NW, suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT:

Jason Yang, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone 781-238-7747, fax 781-238-7199.

SUPPLEMENTARY INFORMATION:

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to Rolls-Royce plc (R-R) RB211-535 series turbofan engines was published in the Federal Register on March 23, 2000 (65 FR 15584). That action proposed to require removal from service of defective radial drive steady bearings manufactured during certain dates and replacement with serviceable parts.

Comments

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.

Requests to Change Compliance Thresholds

Four commenters request that the FAA change the threshold from xxx hours “time-in-service” to xxx hours “since the effective date of this AD.” The commenters state that, based on the fleet utilization rate, in certain cases engines installed with the suspect bearings would be out of compliance on the effective date of this AD.

The FAA agrees. The FAA will revise paragraphs (a)(1) and (a)(2) to read “time-in-service after the effective date of this AD,” instead of “time-in-service-since-new.”

Three commenters request that the FAA increase the thresholds of paragraphs (a)(1) and (a)(2). One commenter requests an increase from 1,500 and 2,400 hours time-in-service (TIS) to 2,100 and 3,300 hours TIS, respectively. A second commenter requests an increase from 1,500 and 2,400 hours TIS to 2,000 and 3,200 hours TIS, respectively. These commenters state that, for the specific operators that will be affected by this AD, at least seven have higher utilization rates. Additionally, operator utilization historically increases during the summer months when the AD will be effective. Therefore, the commenters recommend the respective increases in compliance time in order to avoid a potential disruption to operators. A third commenter requests an increase from 1,500 and 2,400 hours TIS to 1,700 and 2,720 hours TIS, respectively. The commenter states that the proposed limits impose a significant burden as several affected engines will exceed their respective hour limits before reaching their respective calendar days.

The FAA partially agrees with these requests. The FAA will increase the threshold limits in paragraph (a)(1) from 1,500 hours to 1,700 hours TIS after the effective date of this AD. The compliance end date will remain September 30, 2000. The FAA will increase the threshold limits in paragraph (a)(2) from 2,400 hours to 2,720 hours TIS after the effective date of this AD. The compliance end date will remain December 31, 2000.

Request to Use Manufacturer's Calendar Time Limit

One commenter requests that the FAA use the manufacturer's calendar time limit only. The commenter states that the additional 1,500 hour limit placed on the suspect bearings, which is to be calculated from time-since-new, would make certain engines out of compliance from the effective date of the AD. The commenter states that by using only the manufacturer's calendar time limit, the operators would be allowed to source and properly schedule the replacement of these bearings.

The FAA does not agree. The calendar compliance date in the AD was determined by a risk analysis with a normal utilization rate of the engine. To prevent unsafe conditions for certain high usage engines, the AD proposes a calendar compliance date in conjunction with operating hours limits. Additionally, based on other comments received, the “time-in-service-since-new” threshold will be revised in the final rule to “time-in-service after the effective date of this AD.” This change should enable the operators to source and schedule replacement of these bearings.

Revise Economic Analysis

One commenter states that the number of engines installed on aircraft of U.S. registry should be revised. Since only engines that were built new or required a new radial drive steady bearing during the period of July 26, 1998, and September 30, 1999, are affected, the number installed on aircraft of U.S. registry is 102 engines.

The FAA agrees. Based on the revised estimate of 102 affected engines installed on aircraft of U.S. registry, the total cost impact of the AD on U.S. operators is reduced from $160,000 to $40,800. The economic analysis section of the final rule will be revised accordingly.

Clarification of Paragraph (b)(2)

One commenter requests clarification of paragraph (b)(2). The commenter believes that the FAA's intent is that two engines with suspect bearings must not be installed on the same aircraft, until all the suspect bearings are removed per paragraphs (a)(1) and (a)(2). The commenter states that this paragraph, as written, seems redundant and looks like a similar requirement to that of deleted service bulletin RB.211-72-C810.

The FAA does not agree that paragraph (b)(2) is redundant. The intent of paragraph (b)(2) is to prevent the installation of two engines with suspect bearings on the same airplane. This additional requirement ensures that engines with the suspect bearings that have not yet reached the compliance thresholds of paragraphs (a)(1) and (a)(2) will not be installed on the same airplane, thereby reducing the potential for an unsafe condition.

Explanation of Change to Compliance Section

The FAA has revised the compliance section to insert a note on service information. This note references Rolls-Royce Service Bulletin No. RB.211-72-C930, dated December 22, 1999, which provides additional information on identifying and replacing the suspect bearings. This note has been numbered Note 2; the proposed Note 2 has been renumbered Note 3.

Conclusion

After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes described previously. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.

Economic Analysis

There are approximately 1,000 engines of the affected design in the worldwide fleet. The FAA estimates that 102 engines installed on aircraft of US registry will be affected by this AD. It will take approximately 4 work hours per engine to accomplish the required actions. The average labor rate is $60 per work hour. Required parts will cost approximately $160 per engine. Based on these figures, the total cost impact of the AD on US operators is estimated to be $40,800.

Regulatory Impact

This rule does not have federalism implications, as defined in Executive Order 13132, because it does 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.

For the reasons discussed above, I certify that this action (1) is not a “significant regulatory action” under Executive Order 12866; (2) is not a “significant rule” under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action and is contained in the Rules Docket. A copy of it may be obtained from 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

Adoption of the Amendment

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:

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.

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

2000-09-14 Rolls-Royce plc: Amendment 39-11723. Docket No. 2000-NE-04-AD.

Applicability: Rolls-Royce plc RB211-535 series turbofan engines, with radial drive steady bearings with outer race serial number (S/N) prefixes: DLJO, DLJP, DLOQ, DLSK, and DMBA, installed. Affected engines are those that have had a new bearing fitted at overhaul, were new production engines, or had a bearing changed in service between July 26, 1998, and September 30, 1999. These engines are installed on but not limited to Boeing 757 series aircraft and Tupolev Tu204 series aircraft.

Note 1:

This airworthiness directive (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 (c) 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; if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent radial drive steady bearing failure, which could result in an in-flight engine shutdown and smoke and fumes in the cabin, accomplish the following:

Remove Suspect Bearings

(a) Remove from service radial drive steady bearings identified in the applicability paragraph of this AD and replace with serviceable parts as follows:

(1) For engines that had the suspect radial drive steady bearings installed during a shop visit or on-wing, remove from service before accumulating 1,700 hours time-in-service (TIS) after the effective date of this AD, but no later than September 30, 2000.

(2) For engines that had the suspect radial drive steady bearings installed in factory production, remove from service before accumulating 2,720 hours TIS after the effective date of this AD, but no later than December 31, 2000.

Note 2:

Rolls-Royce plc Mandatory Service Bulletin No. RB.211-72-C930, dated December 22, 1999, provides additional information on identifying and replacing the suspect bearings.

Do Not Install Suspect Bearings

(b) As of the effective date of this AD, accomplish the following:

(1) Do not install radial drive steady bearings from the five affected batches listed in the applicability paragraph of this AD at overhaul, in service, or at new production.

(2) If performing an engine change, do not allow two engines that have bearings from any of the five affected batches listed in the applicability paragraph of this AD to be installed on the same airplane.

Serviceable Parts

(3) For the purpose of this AD, serviceable bearings are those which are not listed in the applicability paragraph of this AD. Current outer race S/N prefix DPSF or alphabetically subsequent prefix is considered serviceable.

Alternative Methods of Compliance

(c) 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 shall submit their request through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, ECO.

Note 3:

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

Ferry Flights

(d) Special flight permits may be issued in accordance with §§ 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the aircraft to a location where the requirements of this AD can be accomplished.

Effective Date

(e) This amendment becomes effective on July 11, 2000.