Recently, the FAA has received a report of an accident during which the flight crew executed a missed approach following an instrument landing system (ILS) approach. A McDonnell Douglas Model DC-9-31 series airplane equipped with Honeywell Windshear Detection and Recovery Guidance System (WSS) was involved in this accident. Investigation into the cause of this accident revealed that the airplane encountered severe windshear during the missed approach. The FAA has determined that a design feature in the windshear computer delayed the detection of windshear when the airplane's flaps were in transition. This condition, if not corrected, could result in the flight crew being unaware of the potential for significant delays in the WSS detecting windshear when the flaps of the airplane are in transition.
On February 14, 1995, the FAA issued AD 95-04-01, amendment 39-9153 (60 FR 9619, February 21, 1995), applicable to various transport category airplanes equipped with a Honeywell Standard Windshear Detection and Recovery Guidance System (WSS). That AD requires a revision to the FAA-approved Airplane Flight Manual (AFM) to alert the flight crew of the potential for significant delays in the WSS detecting windshear when the flaps of the airplane are in transition. The actions required by that AD are intended to prevent the flightcrew from failing to realize that the WSS does not detect windshear in a timely manner when the flaps of the airplane are in transition, which could result in loss of control of the airplane.
Since the issuance of that AD, the FAA has identified three additional U.S.-registered airplanes that are equipped with Honeywell WSS and, therefore, subject to the same unsafe condition addressed by AD 95-04-01. The additional airplanes are all Model Avro 146-RJ series airplanes, manufactured by British Aerospace.
This airplane model is manufactured in the United Kingdom and is type certificated for operation in theUnited States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. The FAA has determined that AD action is necessary for products of this type design that are certificated for operation in the United States.
Since an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design registered in the United States, this AD is being issued to ensure that the flight crew of Model Avro 146-RJ series airplanes is aware that there may be significant delays in the WSS detecting windshear when the flaps of the airplane are in transition. This AD requires a revision to the FAA-approved AFM to alert the flight crew of the potential for significant delays in the WSS detecting windshear when the flaps of the airplane are in transition.
This is considered to be interim action. Once a modification is developed, approved, and available, the FAA may consider additional rulemaking.
(NOTE: The FAA's normal policy is that when an AD requires a substantive change, such as a change (expansion) in its applicability, the "old" AD is superseded by removing it from the system and a new AD is added. In the case of this AD action, the FAA normally would have superseded AD 95-04-01 to expand its applicability to include the 3 additional affected airplanes. However, in reconsideration of the entire fleet size that would be affected by a supersedure action (approximately 3,000 U.S. registered airplanes), and the consequent workload associated with revising maintenance record entries, the FAA has determined that a less burdensome approach is to issue a separate AD applicable only to these 3 additional airplanes. Operators should note that this AD does not supersede AD 95-04-01; airplanes listed in the applicability of AD 95-04-01 are required to continue to comply with the requirements of that AD. This AD is a separate AD action, and is applicable only to Model Avro 146-RJ series airplanes equipped with Honeywell WSS having part number 4048300-902.)
Since a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.
Comments Invited
Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.
Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 95-NM-69-AD." The postcard will be date stamped and returned to the commenter.
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 of power 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.
The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, 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. 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 the following new airworthiness directive: