AD 98-11-02 SUPERSEDED

This amendment adopts a new airworthiness directive (AD) that is applicable to all Fokker Model F28 Mark 0070 and Mark 0100 series airplanes. This action requires revising the Airplane Flight Manual (AFM) to provide the flightcrew with instructions not to arm the liftdumper system prior to commanding the landing gear to extend. This amendment is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified in this AD are intended to prevent inadvertent deployment of the liftdumpers during approach for landing, and consequent reduced controllability and performance of the airplane.

Final rule; request for comments.

98-11-02 FOKKER: Amendment 39-10529. Docket 98-NM-153-AD.

Applicability: All Model F28 Mark 0070 and Mark 0100 series airplanes, certificated in any category.

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (b) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent inadvertent deployment of the liftdumpers during approach for landing, and consequent reduced controllability and performance of the airplane, accomplish the following:

(a) Within 5 days after the effective date of this AD, revise the Limitations and Normal Procedures sections of the FAA-approved Airplane Flight Manual (AFM) in accordance with paragraphs (a)(1) and (a)(2) of this AD. This may be accomplished by inserting a copy of this AD in the AFM.

(1) Add the following information to section 5 - Normal Procedures, sub-Section APPROACH AND LANDING, after the subject APPROACH:

"BEFORE LANDING
WARNING: DO NOT ARM THE LIFTDUMPER SYSTEM BEFORE
LANDING GEAR DOWN SELECTION.
Selecting Landing Gear DOWN after arming the liftdumper system may result in inadvertent deployment of the liftdumpers, because the liftdumper arming test may be partially ineffective."

(2) Add the following information to the LIMITATIONS section:

"LIFTDUMPER SYSTEM
DO NOT ARM THE LIFTDUMPER SYSTEM BEFORE LANDING GEAR
DOWN SELECTION."

(b) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, International Branch, ANM-116.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the International Branch, ANM-116.

(c) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

NOTE 3: The subject of this AD is addressed in Dutch airworthiness directive 1998-042 (A), dated April 10, 1998.(d) This amendment becomes effective on June 2, 1998.

The Rijksluchtvaartdienst (RLD), which is the airworthiness authority for the Netherlands, recently notified the FAA that an unsafe condition may exist on all Fokker Model F28 Mark 0070 and Mark 0100 series airplanes. The RLD advises that an inadvertent in-flight liftdumper (spoiler) deployment occurred on an airplane that was on approach for landing. The flightcrew had no indication of a malfunction in the liftdumper system; however, the liftdumper system was armed and the engine throttle levers were set at or close to IDLE. When the flightcrew selected the DOWN position for landing gear, the liftdumpers deployed. Within approximately eleven seconds the liftdumpers retracted, as a result of automatic forward throttle movement and/or flightcrew action to switch off the liftdumper system.

A preliminary investigation of the incident has indicated the cause to be a combination of the following:

- Electro-magnetic interference (EMI) in the outboard wheel speed channels caused by a faulty Flight Control Computer (FCC);

- Voltage spikes in the inboard wheelspeed channels during skid control box power-up on landing gear DOWN selection; and

- Liftdumper arming prior to landing gear DOWN selection.
Fokker and the RLD are continuing to investigate the cause of the incident.

Such inadvertent deployment of the liftdumpers during approach for landing, if not corrected, could result in reduced controllability and performance of the airplane.

Explanation of Relevant Service Information
Fokker has issued All Operator Message (AOM) AOF100.044, dated April 8, 1998, which provides procedures to revise the Airplane Flight Manual (AFM) to provide the flightcrew with instructions not to arm the liftdumper system before commanding the landing gear to extend. The RLD issued Dutch airworthiness directive 1998-042 (A), dated April 10, 1998, mandating the these instructions into the AFM, in order to assure the continued airworthinessof these airplanes in the Netherlands.

FAA's Conclusions
These airplane models are manufactured in the Netherlands and are type certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, the RLD has kept the FAA informed of the situation described above. The FAA has examined the findings of the RLD, reviewed all available information, and determined that AD action is necessary for products of this type design that are certificated for operation in the United States.

Explanation of Requirements of Rule
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 prevent inadvertent deployment of the liftdumpers during approach for landing, and consequent reduced controllability and performance of the airplane. This AD requires revising the Limitations and Normal Procedures sections of the FAA-approved AFM to provide the flightcrew with instructions not to arm the liftdumper system prior to commanding the landing gear to extend.

Differences Between This AD and the Dutch Airworthiness Directive
This AD differs from the parallel Dutch airworthiness directive in that the AFM revision is reworded to include a more specific statement of the consequence of arming the liftdumper before commanding the landing gear to extend. The FAA has determined that the Limitations and Normal Procedures sections of the AFM must be revised to inform the flightcrew that arming the liftdumper before commanding the landing gear to extend may result in inadvertent deployment of the liftdumper.

Interim Action
This is considered to be interim action until final action is identified, at which time the FAA may consider further rulemaking.

Determination of Rule's Effective Date
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 98-NM-153-AD." The postcard will be date stamped and returned to the commenter.

Regulatory Impact
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. 106(g), 40113, 44701.

39.13 [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 98-NM-153-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.
Information pertaining to this amendment may be obtained from or examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

Norman B. Martenson, Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2110; fax (425) 227-1149.