01-21398. Airworthiness Directives; Rolls-Royce Corporation (Formerly Allison Engine Company) 250-C18 and C-20 Series Turboshaft Engines

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Proposed rule; withdrawal.

SUMMARY:

This action withdraws a notice of proposed rulemaking (NPRM) that proposed a new airworthiness directive (AD), applicable to Rolls-Royce Corporation (formerly Allison Engine Company) 250-C18 and C-20 series turboshaft engines. That action would have required a one-time visual inspection of the fuel nozzle screen for contamination. If contamination is found, the proposal would have required, prior to further flight, replacement of the fuel nozzle screen with a serviceable screen, visual inspection of the entire fuel system for contamination, and repair, if necessary. In addition, this proposal would have required reporting the results of the one-time inspection to the Federal Aviation Administration (FAA) to determine if repetitive inspections should be required by further rulemaking. This proposal was prompted by a report of fuel system contamination that caused an in-flight engine shutdown, autorotation, and forced landing. Since the issuance of the NPRM, the FAA and Rolls-Royce have determined that there have been no additional engine problems reported due to fuel nozzle screen contamination. Accordingly, the proposed rule is withdrawn.

FOR FURTHER INFORMATION CONTACT:

John Tallarovic, Aerospace Engineer, Chicago Aircraft Certification Office, FAA, Small Airplane Directorate, 2300 E. Devon Ave., Des Plaines, IL 60018; telephone [phone], fax [phone].

SUPPLEMENTARY INFORMATION:

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to add a new AD that is applicable to Rolls-Royce Corporation (formerly Allison Engine Company) 250-C18 and C-20 series turboshaft engines was published in the Federal Register on April 25, 2000 (65 FR 24135). That action proposed to require a one-time visual inspection of the fuel nozzle screen for contamination. If contamination is found, that proposal would have required, prior to further flight, replacement of the fuel nozzle screen with a serviceable screen, visual inspection of the entire fuel system for contamination, and repair, if necessary. In addition, that proposal would have required reporting the results of the one-time inspection to the Federal Aviation Administration (FAA) to determine if repetitive inspections should be required by further rulemaking. The actions specified by the proposal were intended to prevent an in-flight engine shutdown due to blockage of the fuel nozzle screen, which can result in autorotation and forced landing.

Since the issuance of that NPRM, the FAA and Rolls-Royce have determined that there have been no additional engine problems reported due to fuel nozzle screen contamination. Rolls-Royce further maintains that fuel nozzle contamination is a very rare event, varying between zero to 6.5 per 8,000 disassembled nozzles.

Since this problem first surfaced, Rolls-Royce and the FAA have taken the following actions:

• Because most accidents involving fuel nozzle contamination have occurred in Hawaii, Rolls-Royce Corporation conducted a training/fact finding mission to Hawaii in the spring of 1998 to assess the situation and to help educate users regarding the proper service of engine fuel systems.
• The FAA approved revised maintenance procedures for the Rolls-Royce model 250 engines. These procedures clarified the actions to be taken when fuel system contamination is suspected.
• Finally, the FAA published Special Airworthiness Information Bulletin (SAIB) No. CE-01-10 advising owners and operators of Rolls-Royce Corporation model 250-C18 series and 250-C20 series engines of the recent changes to the fuel system maintenance on how rotorcraft engine fuel nozzle screens be inspected.

Comments Received

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

Support

Two commenters either supported the NPRM or were neutral.

Opposition to NPRM

One commenter points out that there is already a requirement to inspect the fuel nozzle screen each 300 hours of operation if there is no airframe mounted fuel filter (otherwise inspect it at 1,500 hours); a 300 hour requirement to replace the fuel filter, and a 1,000 hour requirement to change the fuel control screen. The commenter expresses concern that the proposed actions in the NPRM would burden the majority of the operators who are already correctly performing the required maintenance checks. The FAA agrees and the NPRM is being withdrawn.

Another comment, by an aircraft owner and repair station owner employing over 200 Airframe and Powerplant mechanics, strongly opposes the actions proposed in the NPRM. The commenter emphasizes that efforts should be put into ensuring that clean fuel is used by operators, rather than mandating items that are already clearly covered by the Original Equipment Manufacturer's maintenance and operations manuals. The comment also notes that the rare cases of contamination they had witnessed resulted from operators refueling remotely out of 55-gallon drums. The commenter believes that this is an operational issue rather than an inherent design flaw with the rotorcraft fuel system. The FAA agrees. This observation is consistent with the FAA's inspection results confirming that accidents involved cases where the fuel supply was a problem (less than optimal conditions).

The final comment opposing the NPRM is from an owner/operator of 173 helicopters. This individual also points out that the actions proposed in the NPRM were already required by the engine maintenance manual. He expresses concern that in the course of complying with the proposed actions in the NPRM, mechanics will be removing and disassembling thousands of fuel nozzles in the field. It is his experience that these nozzles are best taken apart at a repair facility where they can be checked for proper reassembly after the inspection. Due to the critical nature of the assembly process, slight variations in the torque values can have a significant effect on the fuel flow and spray pattern of the nozzle. The net result would be an increase in service difficulties associated with the fuel nozzle. The FAA agrees and the proposed NPRM is being withdrawn.

After further consideration and review of this data, the FAA has determined that the unsafe condition no longer exists and is extremely unlikely to develop. Accordingly, the proposed rule is withdrawn.

Withdrawal of this notice of proposed rulemaking does not preclude the agency from issuing another notice in the future, nor does it commit the agency to any course of action in the future.

Since this action only withdraws a notice of proposed rulemaking, it is neither a proposed nor final rule, and, therefore, is not covered under Executive Order 12866, the Regulatory Flexibility Act, or DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979).

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Withdrawal

Accordingly, the notice of proposed rulemaking, Docket No. 99-NE-47, published in the Federal Register on April 25, 2000 (65 FR 24135), is withdrawn.

Issued in Burlington, Massachusetts, on August 16, 2001.

Jay J. Pardee,

Manager, Engine and Propeller Directorate, Aircraft Certification Service.