02-8281. Airworthiness Directives; McDonnell Douglas Model DC-8 Series Airplanes

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 all McDonnell Douglas Model DC-8 series airplanes. That action would have required incorporation of horizontal stabilizer position information into the existing takeoff configuration warning system. Since the issuance of the NPRM, the Federal Aviation Administration (FAA) has received new data that indicate that the identified unsafe condition does not exist. Accordingly, the proposed rule is withdrawn.

FOR FURTHER INFORMATION CONTACT:

George Y. Mabuni, Aerospace Engineer, Systems and Equipment Branch, ANM-130L, FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California 90712-4137; 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 airworthiness directive (AD), applicable to all McDonnell Douglas Model DC-8 series airplanes, was published in the Federal Register as a Notice of Proposed Rulemaking (NPRM) on November 30, 1988 (53 FR 48499). The proposed rule would have required incorporation of horizontal stabilizer position information into the existing takeoff configuration warning system. That action was prompted by an FAA review of takeoff configuration warning systems of large turbofan/turbojet transport airplanes. The review revealed that the horizontal stabilizer position was not monitored by the takeoff warning system on Model DC-8 series airplanes. The proposed actions were intended to prevent an airplane from taking off in the wrong takeoff configuration.

Since Issuance of the NPRM

Since the NPRM was issued, we have engaged in additional research into the identified unsafe condition and potentially related accidents and found that incorrect loading data—and not unsafe flight crew procedures—may have resulted in a miscalculated center of gravity on takeoff. Incorrect trim setting was cited or at least suspected as a factor in three accidents. There are a number of possible explanations for an incorrect trim setting: The pilot may have misread the loading data, the company flight operations department may have provided incorrect data, or the pilot may have erred in calculating and setting the trim. To be effective, an out-of-trim warning system requires accurate takeoff data from the pilot; therefore, it is not clear whether input error may have been involved or whether any of the accidents would have actually been prevented by an out-of-trim warning system.

We find that established crew procedures are sufficient to maintain the necessary level of safety. Notwithstanding the three accidents discussed above, the remaining service experience on Model DC-8 series airplanes (and most other airplanes of that vintage) confirms the effectiveness and adequacy of flight crew procedures in ensuring the correct takeoff setting of the horizontal stabilizer when the flight crew is provided correct information. In light of these findings, we have determined that the previously identified unsafe condition does not exist—provided the flight crew follows established takeoff procedures.

Furthermore, the economic impact of the proposed AD on operators would be significant. Five commenters to the NPRM indicated that accomplishment of the actions of the proposed AD would impose a significant economic burden. The cost of the modification kits would be high because the manufacturer must design, test, and certify the system before kits can be made available to the operators. The estimated total cost to accomplish the proposed actions would be $149,000 per airplane (adjusted for inflation from the date of the proposed AD). In fact, the cost of implementing the proposed requirements could exceed the value of the entire fleet. In light of our determination that an unsafe condition does not exist, we find that the large economic impact to mandate incorporation of the proposed system on these airplanes is impractical and unjustified.

FAA's Conclusions

Upon further consideration, we have determined that the unsafe condition identified in the proposed AD does not exist. 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 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 88-NM-145-AD, published in the Federal Register on November 30, 1988 (53 FR 48499), is withdrawn.

Issued in Renton, Washington, on March 28, 2002.

Kalene C. Yanamura,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.