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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 2002-NM-257-AD] 
          - RIN 2120-AA64 

# 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 certain Airbus Model A319, A320, and A321 series airplanes. That action would have required replacement of the lightweight tailpipes of the auxiliary power units (APU). Since the issuance of the NPRM, the Federal Aviation Administration (FAA) has received additional information, based on which we have determined that the tailpipes are very light, and that the chances of any injury to persons or damage to equipment from the part being ejected from the APU exhaust duct are minimal. Also, we have determined that 100 percent of the U.S. operators have done the proposed replacement. Accordingly, the proposed rule is withdrawn. 

# FOR FURTHER INFORMATION CONTACT:

Gary Lium, Aerospace Engineer; International Branch, ANM-116, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-1112; fax (425) 227-1149. 

# SUPPLEMENTARY INFORMATION:

                    A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to add a new airworthiness directive (AD), applicable to certain Airbus Model A319, A320, and A321 series airplanes, was published in the                     **Federal Register**                     as a Notice of Proposed Rulemaking (NPRM) on June 18, 2004 (69 FR 34096). The proposed rule would have required replacement of the lightweight tailpipes of the APU. That action was prompted by reports that stress cracking stemming from design issues had been discovered in the inner liners of the lightweight tailpipes of certain APUs. The proposed actions were intended to prevent stress cracking of the tailpipe inner liner from possibly causing the tailpipe to become separated from the APU during operation, which could have posed a hazard to persons on the ground.                 

## Actions that Occurred Since the NPRM Was Issued 

Since the issuance of that NPRM, we have received additional information. The failed part, a sheet metal ring that forms a portion of the tailpipe, weighs less than one pound. If the part does fail and come off, it will blow out the back and not interfere with continued APU or airplane operation. We have determined that the probability of any injury to persons or damage to equipment from the part being ejected from the APU exhaust duct is minimal. Also, we have determined that 100 percent of the U.S. operators have done the proposed replacement. 

## FAA's Conclusions 

Upon further consideration, the FAA has determined that the identified unsafe condition does not exist on the affected airplanes. Accordingly, the proposed rule is hereby withdrawn. 

Withdrawal of this NPRM constitutes only such action, and does not preclude the agency from issuing another action in the future, nor does it commit the agency to any course of action in the future. 

## Regulatory Impact 

                    Since this action only withdraws a notice of proposed rulemaking, it is neither a proposed nor a final rule and therefore is not covered under Executive Order 12866, the Regulatory Flexibility                           ( print page 58112)                        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 2002-NM-257-AD, published in the                     **Federal Register**                     on June 18, 2004 (69 FR 34096), is withdrawn.                 

Issued in Renton, Washington, on September 20, 2004. 

Kalene C. Yanamura, 

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. 

[FR Doc. 04-21817 Filed 9-28-04; 8:45 am] 

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