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 Terra Corporation TRT 250 series transponders was published in the Federal Register on May 26, 1994 (59 FR 27249). The original comment period was open for 30 days. However, subsequently, the FAA determined that the original comment period was inadequate and reopened the comment period on September 6, 1994 (59 FR 46007) with no additional changes in the proposed rule. That action proposed to require removing the transponder from the aircraft, inspecting it to determine if the AD applies, and replacing any affected transponder with a modified Terra Corporation transponder or another transponder that responds properly to Mode S interrogations from both an ATCRBS/Mode S ground station and TCAS II airborne equipment.
Interested persons have been afforded an opportunity to participate in the making of this amendment. Thirty-four comments were received from thirty-one commenters. Three of the commenters responded twice and two commenters commented on two different items contained in the Notice of Proposed Rulemaking (NPRM). Due consideration has been given to the comments received. Two commenters request that certain information be included in the preamble language that further explains the history behind these transponders and this AD. These commenters request that language be inserted in the final rule stating that: (1) these transponders have been produced since 1985; (2) these transponders meet the requirements of Technical Service Order (TSO)-C74c; (3) the Mode S ground stations and the TCAS II airborne equipment interrogates beyond the ATCRBS interrogation for which these transponders were designed instead of stating that the Mode S and TCAS II interrogates beyond the P3 pulse; and (4) the economic analysis that shows the $298 as the cost of the required parts not only includes thecost of the parts, but also the labor required to modify the affected transponders. While the FAA agrees with the substance of these comments, they are not proposing any changes to the AD language; therefore, no changes are made to the AD based upon these comments.
Four commenters state that this AD should be published as an immediately adopted final rule because of its serious safety implications. The FAA does not concur. The FAA determined that, based upon the impact of the proposed requirements of this AD, it was appropriate to acquire as many public comments as possible prior to finalizing the actions. Therefore, the FAA published an NPRM soliciting public comments. To ensure the safety of flight, the Mode S ground stations are temporarily altered to permit the affected transponders to respond properly to ATCRBS interrogations during the compliance period.
Another two commenters state that there is no justification for an extended compliance period and that complianceshould be required as soon as possible. The FAA does not concur that a compliance time of less than 6 months is appropriate. With an estimated 5,000 transponders in the field that require replacement or modification, a compliance time of less than 6 months would not allow adequate time for all transponders to be modified or replaced.
Two commenters state that longer compliance times should be provided within which to modify these transponders because no significant safety hazard exists. The FAA does not concur. In April 1994, Terra Corporation notified its customers of the forthcoming FAA AD against the TRT 250 series transponders. The FAA informed the public via the NPRM process in May 1994, and provided a 30-day comment period. The comment period for the NPRM was reopened in September 1994 to provide another 60 days for additional comments. Public notices appeared in several aviation trade publications during this period. The manufacturer indicates that several hundred transponders have been modified since the May 1994 publication of the NPRM. Transport aircraft that utilize TCAS II and Mode S transponders cannot detect those aircraft equipped with a Terra transponder built according to the requirements of TSO-C74c. As a direct result of the Terra transponder problem, a thorough evaluation and a complete implementation of Mode S ground sensors cannot occur until the transponders are modified. In summary, this AD establishes the existence of an aviation safety problem, and the FAA has allowed an appropriate compliance time for action by owners or operators.
One commenter states that the FAA employee or employees involved with the approval of the original transponder's design should pay for the costs of modifying the transponders. The FAA does not concur. The FAA as an agency is responsible for all directives, policies, mandates, etc., issued under its authority, and does not penalize employees for actions committed in good faith and within thescope of their duties.
Twenty-two commenters state that since the FAA is responsible for the transponder's design problems, either because of the FAA's short-sighted approval of the TSO used to produce these transponders, or because it decided to implement the Mode S ground sensors without adequate research and testing to determine whether all transponders would respond properly to the interrogations, the FAA should bear the costs associated with modifying these transponders. The FAA does not concur with the commenters. Although the FAA has determined that a safety problem exists with the transponder's design, the manufacturer is responsible for the design. The technical performance standards for airborne air traffic control (ATC) transponder equipment (TSO-C74c) were developed by a committee comprised of both government and industry representatives. A representative of the transponder manufacturer is included on the membership list for that committee. There have been no reports of other manufacturers having a similar transponder design deficiency. Additionally, the FAA's budget does not include allocations to cover AD costs incurred in modifying privately-owned equipment.
Since the issuance of the NPRM, the manufacturer has issued Revision 1 to Mandatory Service Bulletin (MSB) No. SB-104 on June 27, 1994. This revision adds an additional optional modification method to the original MSB No. SB-104, dated March 14, 1994, that was proposed to be incorporated by reference in the NPRM. Since the revised MSB imposes no additional burden on operators and is an optional relieving provision, MSB No. SB-104, Revision 1, dated June 27, 1994, is incorporated by reference in this final rule. Additionally, since the issuance of the NPRM, the FAA has reevaluated the labor rate, and based upon this evaluation, has increased the hourly labor rate to $60 per work hour instead of the proposed $55 per work hour. This change increases the estimated overall cost of this AD by $37,500 to $1,940,000.
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 only editorial changes and 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.
The FAA estimates that 5,000 aircraft of U.S. registry will be affected by this AD, that it will take approximately 1.5 work hours per aircraft to accomplish the required actions, and that the average labor rate is $60 per work hour. Required parts will cost approximately $298 per aircraft. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $1,940,000.
The regulations adopted herein will not have substantial direct effects on the States, on the relationship between the national government and the States, or on the distribution ofpower and responsibilities among the various levels of government. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.
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 it 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, Incorporation by reference,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. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89.
39.13 - [Amended]
2. Section 39.13 is amended by adding a new airworthiness directive to read as follows: