00-1772. Airworthiness Directives; de Havilland Model DHC-8-100, -200, and -300 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Final rule.

SUMMARY:

This amendment adopts a new airworthiness directive (AD), applicable to all de Havilland Model DHC-8-100, -200, and -300 series airplanes, that requires installation of a placard on the instrument panel of the cockpit to advise the flightcrew that positioning of the power levers below the flight idle stop during flight is prohibited. This amendment also requires eventual installation of a system that will prevent such positioning of the power levers during flight. Such installation will terminate the requirement for installation of a placard. This amendment is prompted by reports of operation of the airplane with the power levers positioned below the flight idle stop during flight. The actions specified by this AD are intended to prevent such positioning of the power levers below the flight idle stop during flight, which could cause engine overspeed, possible engine damage or failure, and consequent reduced controllability of the airplane.

EFFECTIVE DATE:

March 1, 2000.

FOR FURTHER INFORMATION CONTACT:

James E. Delisio, Aerospace Engineer, Airframe and Propulsion Branch, ANE-171, FAA, Engine and Propeller Directorate, New York Aircraft Certification Office, 10 Fifth Street, Third Floor, Valley Stream, New York 11581; telephone [phone]; fax [phone].

ADDRESSES:

Information pertaining to this amendment may be examined at the Federal Aviation Administration (FAA), Transport Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Engine and Propeller Directorate, New York Aircraft Certification Office, 10 Fifth Street, Third Floor, Valley Stream, New York.

SUPPLEMENTARY INFORMATION:

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 all de Havilland Model DHC-8-100, -200, and -300 series airplanes was published in the Federal Register on July 7, 1998 (63 FR 36619). That action proposed to require installation of a placard on the instrument panel of the cockpit to advise the flightcrew that positioning of the power levers below the flight idle stop during flight is prohibited. Additionally, that action proposed to require eventual installation of an FAA-approved system that would prevent such positioning of the power levers during flight. Installation of that system would eliminate the requirement for installation of the placard.

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.

1. Support for the Proposal

One commenter supports the proposed rule.

2. Request to Withdraw the Proposal: No Unsafe Condition

Several commenters point out the following: No new incidents of beta during flight have been reported since 1996, and reports were from foreign operators. Since those previous reports, the AFM has been revised to prohibit positioning of the power levers below the flight idle stop (beta) during flight, and the pilot training syllabus on prohibition of beta during flight has been revised. The commenters further state that sufficient tactile, visual, and audio cues exist to advise the flightcrew if the propeller is in beta range. One commenter, the manufacturer, points out that the power lever triggers cannot be applied accidentally. Movement of the triggers requires purposeful “reach and lift” action to engage beta. Therefore, the manufacturer asserts that unintentional engagement of beta during flight cannot occur. Another commenter states that a mechanical system cannot preclude inappropriate operation; however, proper training of pilots can. These commenters conclude that, with the previously mentioned procedures already in place, the unsafe condition specified in the proposed rule does not exist.

The FAA does not concur that the subject unsafe condition does not exist in Model DHC-8 series airplanes. The FAA acknowledges that other safeguards currently in practice, such as AFM revisions and the revised pilot training syllabus, do provide certain tactile, visual, and audio cues. (See Comment 7 for related discussion on visual cues.) However, despite the implementation of those safeguards, the FAA has received reports of operation of the airplane with the power levers positioned below the flight idle stop during flight on de Havilland Model DHC-8 series airplanes. One report indicated that such operation resulted in significant engine damage. Therefore, the FAA considers that sufficient data exist to demonstrate that an unsafe condition exists on Model DHC-8 series airplanes. Further, the FAA has determined that positioning of the power levers below the flight idle stop could result in engine overspeed, possible engine damage or failure, and consequent reduced controllability of the airplane.

3. Request to Withdraw the Proposal: Airplane Already Meets Intent of 14 CFR Part 25.1155

Several commenters state that the current design meets the requirements of part 25 of the Federal Aviation Regulations (14 CFR part 25.1155), and one other commenter asserts that the current design already goes beyond those requirements. One of the commenters points out that part 25 of the Federal Aviation Regulations (14 CFR part 25) only addresses unintentional or uninformed actions, and does not address intentional acts. Another commenter states that if the FAA is going beyond its statutory authority and being inconsistent in application of requirements without providing justification, the commenter would view the proposed rule as arbitrary rulemaking.

The FAA does not concur that the AD should be withdrawn. The issuance of this AD is based on the finding that an unsafe condition exists or is likely to develop in this airplane series. The FAA points out that an airplane's type design is approved only after the FAA makes a determination that it complies with all applicable part 25 (14 CFR part 25) airworthiness requirements. In adopting and maintaining those requirements, the FAA has made the determination that they establish an appropriate level of safety. However, actual in-service experience (as well as other factors, such as manufacturers' fatigue testing, etc.) may reveal problems in an airplane or its components that were not envisioned or predictable at the time of type certification. When these problems create an unsafe condition, this means that the intent of the original level of safety is no longer being achieved. When actions or procedures have been identified that will positively correct the unsafe condition and restore the airplane to its original level of safety, an AD is the appropriate vehicle for mandating that such actions be accomplished.

4. Request to Withdraw the Proposal: Proposed Installation May Introduce an Unsafe Condition

Several commenters state that introduction of a beta lockout system will not provide any added safety benefit, and could actually cause an unsafe condition if the beta lockout system were to fail during landing. These commenters point out that failure of the lockout system to release may prevent the selection of propeller beta pitch angles (on the ground after landing) could, in fact, cause an over run, loss of control of the airplane during landing, or an accident. This commenter also states that with an “override” function, the flightcrew is required to perform an additional task to unlock the power levers so they can select “Beta/Disking & Reverse.” Another commenter states that installation of a mechanical lockout system would require an additional cockpit procedure and associated training. That commenter points out that such an additional cockpit procedure would contribute to the crew workload during the most critical phase of flight. Further, the commenter contends that the additional cockpit procedure could result in delay in placing the airplane in the desired configuration when required.

The FAA does not concur that the installation of a beta lockout system may introduce an unsafe condition. The FAA has already required retrofit of a similar lockout system on three other turbopropeller-powered airplane models. Further, several turboprop airplanes were designed and certified with beta lockout systems. Both the retrofit and the original designed lockout systems have been operating safely for close to ten years with no adverse landing or rollout service history. No change is required to the final rule as a result of these comments.

5. Request to Delay Issuance of the Final Rule

Two commenters state that the proposed rule is premature and inconsistent, and that any rulemaking effort should wait until the Aviation Rulemaking Advisory Committee (ARAC) submits its findings and recommendations regarding a change to the Federal Aviation Regulations. One of those commenters points out that ARAC is not expected to submit its recommendations to the FAA until July 31, 2001. That commenter contends that, until changes to part 25 of the Federal Aviation Regulations have been accomplished, the proposal is premature, and, at best, shows an inconsistency by the FAA as a result of arbitrary rulemaking without explanation. Another commenter requests that the FAA delay issuance of a rule pending a detailed safety study review of the current design, with the objective of determining if the Bombardier design proposal for a beta warning horn addresses the unsafe condition.

The FAA does not consider that delaying this action until after the release of the ARAC recommendation is warranted since sufficient technology currently exists to devise and install a beta lockout system. The purpose of the ARAC task is to determine whether changes to existing design standards are appropriate. These standards would be applicable only to future designs. In tasking ARAC on this subject, the FAA never intended that ARAC address issues relating to unsafe conditions found on previously certificated designs. Further, the FAA has determined that the warning horn is not sufficient to address the unsafe condition, and does not prevent moving the power lever into the beta range during flight.

6. Request to Revise Paragraph (b) of the Proposal

Several commenters request that the FAA require installation of a beta warning horn rather than the beta lockout modification required by paragraph (b) of the proposal. These commenters also point out that Transport Canada Civil Aviation (TCCA), which is the airworthiness authority for Canada, did not determine that a beta lockout system was necessary. Those commenters question why the FAA has determined that installation of the beta lockout system is necessary when TCCA has not mandated such an installation. One commenter, the manufacturer, states that TCCA is planning to require mandatory installation of the beta warning horn, which would be substantially less expensive than installation of a beta lockout system, and would still provide an equivalent level of safety. Some commenters state that the description of the installation specified in paragraph (b) of the proposal is not sufficient to provide actual guidelines for the development of a beta lockout system. However, another commenter states that paragraph (b) of the proposal limits how operators can comply with the requirements.

Another commenter requests that specific training for prohibiting beta during in-flight be required instead of the beta lockout system. Additionally, another commenter states that the service experience of the Model DHC-8 series airplane does not distinguish itself in comparison to other airplane models considering the fact that crews of other types of airplanes could intentionally position the power lever in the beta range.

Other commenters state that a beta lockout system still wouldn't preclude intentional use of beta during flight because of the override function. The manufacturer states that the proposal implies that installation of a beta lockout system would preclude the pilot from being able to position the power lever below flight idle during flight. However, the manufacturer points out that with an override function, intentional positioning of the power levers below the flight idle stop during flight cannot be prevented. The manufacturer concludes, therefore, that the declared unsafe condition cannot be eliminated by the installation of a beta lockout system with an override function. The manufacturer asserts that, if it can be concluded that intentional positioning of power levers below flight idle stop during flight can only be deterred, the beta warning horn provides such deterrence. The manufacturer states that a beta warning horn provides a loud, easily identifiable aural warning, which would “sound” with any movement of the power levers below the flight idle stop. The manufacturer further notes that TCCA has accepted the beta warning horn modification as an enhanced level of safety.

The FAA does not concur with the requests to revise the requirement specified in paragraph (b) of the final rule. The FAA acknowledges that additional airplane flight manual limitations and additional pilot training have enhanced the operational safety of the airplane. However, those actions have not proven to solve the long-term problem involving unsafe operation of other turbopropeller-powered airplanes with a similar throttle quadrant design and service histories involving unsafe operation. Despite the addition of those actions, reports of beta during flight continued.

Further, the FAA does not concur with the commenters' requests to require a beta warning horn in lieu of a beta lockout system. The FAA points out that it appears that certain actions taken by the flightcrew are reflexive, and, as such, the action of placing the power levers below flight idle during flight may not always be interrupted by the horn. Additional data indicate that if beta operation is attempted with a warning horn as the only safety system, it is possible that in the time it takes for the flightcrew to react and return the power levers to the flight range, an overspeed of the propeller could occur that might cause engine damage or failure, and consequent reduced controllability of the airplane. Further, the beta horn (even though distinctive) may be accompanied by an airplane overspeed warning horn, along with other warnings, which may be confusing to the flightcrew. The FAA points out that, in at least one previous accident caused by inflight beta uses on another turbpropeller-powered airplane, the pilot attempted to decelerate the airplane from an overspeed condition (airplane speed was initially above Vmo). In that case, the airspeed aural warning was already sounding at the time the inflight beta event occurred. The FAA notes that many transport category airplanes powered by turbopropeller engines are operated at or near Vmo during descent in order to maintain adequate Air Traffic Control (ATC) separation from the faster flying turbojet-powered airplanes. Therefore, the FAA considers that use of a beta warning horn could be preceded or accompanied by an airplane overspeed aural warning, and could result in confusion to the flightcrew. Although the FAA acknowledges that a beta warning horn should deter the pilot from using beta in flight, the horn does not physically keep the power levers from being placed in the beta mode during flight. As explained previously, several turbopropeller-powered airplanes were designed and certified with beta lockout systems, and the FAA has required retrofit of a similar lockout system on three other turbopropeller-powered airplane models. Both the original design lockout systems and the retrofit have been operating safely for close to ten years with acceptable landing or rollout service history.

In response to commenters that questioned why the FAA is requiring installation of a beta lockout system and TCCA has not, the FAA notes that, while the United States and Canada observe the provisions of the bilateral airworthiness agreement, it remains the responsibility of the FAA to monitor and maintain the continuing airworthiness of U.S-type certificated and -registered airplanes. The bilateral airworthiness agreement does not restrict the FAA from issuing AD's based upon its own finding of an unsafe condition, regardless of the decision relative to the same subject made by another airworthiness authority. The FAA has examined the reports of operation of the airplane with the power levers positioned below the flight idle stop during flight on Model DHC-8 series airplanes, has examined other available data, and has determined that an unsafe condition exists. Therefore, the FAA finds that AD action is necessary for airplanes of this type design that are certificated for operation in the United States.

In reponse to the commenter's statement that paragraph (b) of the proposed rule limits the ways operators can comply with the requirements, the FAA points out that the language specified in that paragraph is purposefully general in nature to allow for some flexibility by the operators in complying with the requirements of that paragraph. Further, the FAA also points out that paragraph (d) of the final rule also contains a provision for operators to request approval of an alternative method of compliance.

7. Requests to Revise Paragraph (c) of the Proposal

One commenter requests that the proposed allowance for Minimum Master Equipment List (MMEL) relief of two days, as specified in paragraph (c) of the proposal, be extended to three days. Another commenter, the manufacturer, states that, where a legitimate system failure has necessitated the use of the override system, operators should not be penalized with a mandatory maintenance action in order to dispatch the airplane. The manufacturer considers a lockout system to be a secondary non-essential system to the existing design, and, therefore, dispatching the airplane with a failed lockout system for a limited time would not jeopardize the safety of the airplane. The manufacturer further states that if a pilot chooses to use the override system just prior to touchdown during inclement weather (e.g., low visibility, contaminated runway), those conditions could be considered emergency situations. Use of an override system in such an emergency should not require maintenance action to return the airplane to dispatch configuration. For those reasons, the manufacturer requests that the proposed MMEL relief of two days be extended in accordance with criteria to be identified in the DHC-8 MMEL.

The FAA concurs that the MMEL relief specified in paragraph (c) of the proposal may be extended to three flight days. However, although use of the override system may be made available as a means to gain additional stopping performance in the event of a failed beta lockout system, the FAA does not consider low visibility or contaminated runway scenarios to constitute an emergency. Further, the override function is used only when a system failure or potentially inadequate ground/air logic is indicated while the airplane is on the ground. The FAA has determined that in those situations a maintenance action must be taken.

8. Request to Require Only the Placard Installation

One commenter contends that the only action that the FAA should require is the installation of a placard. The commenter asserts that adding the placard, in combination with the current pilot training curriculum, provides an adequate level of safety. The commenter further points out that only a placard is necessary for many other airplane models.

The FAA does not concur that installation of the placard should be the only requirement of this AD. The FAA has determined that long-term continued operational safety will be better assured by design changes to remove the source of the problem, rather than by reliance upon visual cues such as placards. Such visual cues may not be providing the degree of safety assurance necessary for certain transport airplanes. This, coupled with a better understanding of the human factors associated with reliance upon visual cues, has led the FAA to consider placing less emphasis on such visual cues and more emphasis on design improvements. The required installation of a beta lockout system is consistent with these considerations.

The FAA acknowledges that installing a placard is the only requirement for some transport airplanes. Those airplanes, however, do not have the same service experience as Model DHC-8 series airplanes. As explained in Comment 6, the FAA has required the installation of a beta lockout system on other airplane models that have similar service experiences to those of Model DHC-8 series airplanes.

9. Request to Extend the Compliance Time

One commenter, the manufacturer, requests that the compliance time for the installation of the beta lockout system be revised from one year to 21/2 years. The manufacturer explains that a beta lockout design could be available within one year of being mandated, but cautions that a compliance time of 18 months after the design approval is necessary.

Two other commenters request that the compliance time be changed to two years to allow time for design approval and actual installation. One other commenter states that one year is not enough time, but does not suggest an alternative compliance time.

The FAA concurs that the compliance time to install the beta lockout system may be extended somewhat. The FAA has taken into consideration the complexity of accomplishing the installation of a beta lockout system and the time that will be needed to develop and approve a service bulletin, and has concluded that a two-year compliance time to install the beta lockout system may be established without adversely affecting safety. Paragraph (b) of the final rule has been revised accordingly.

10. Requests to Revise the Cost Estimate

One commenter, the manufacturer, considers the cost estimate provided in the proposal to be significantly lower than actual costs. The manufacturer states that it has information indicating that the lockout implementation on another airplane model is estimated at an average of $24,000 per airplane ($12,000 for parts and $12,000 for labor). The manufacturer points out that the proposal does not account for the potential loss of revenue incurred by airplane downtime for incorporation of the change. The manufacturer is concerned that the lower cost estimate of $17,800 in the proposal may be misleading to operators.

One commenter considers that the requirements of the proposal go beyond the current requirements for continued airworthiness; therefore, the costs that were disregarded in the proposal as necessary for “maintaining a safe airplane” should be attributed solely as a direct result of the AD and should be addressed as such. Another commenter requests an explanation as to why a complete cost-benefit analysis is unnecessary and redundant. That same commenter requests that the FAA provide a cost-benefit analysis before a determination is made to require actions that may be unnecessary for an airplane that is already safe.

Based on information provided by the manufacturer, the FAA concurs that the estimated cost for the installation of the beta lockout system should be adjusted, and has revised the final rule accordingly. However, the FAA does not concur that a cost-benefit analysis should be accomplished for this AD. As stated in the proposal, as a matter of law, in order to be airworthy, an aircraft must conform to its type design and be in a condition for safe operation. The type design is approved only after the FAA makes a determination that it complies with all applicable airworthiness requirements. In adopting and maintaining those requirements, the FAA has already made the determination that they establish a level of safety that is cost-beneficial. When the FAA, as in this AD, makes a finding of an unsafe condition, this means that the original cost-beneficial level of safety is no longer being achieved and that the actions are necessary to restore that level of safety. Because this level of safety has already been determined to be cost-beneficial, a full cost-benefit analysis for this AD would be redundant and unnecessary.

11. Request to Clarify Intent of the Proposed Rule

Several commenters request that an accurate description of the unsafe condition be provided. Other commenters request clarification as to whether the FAA is trying to prevent an unsafe condition that could be caused by unintentional pilot actions or by intentional pilot actions.

The FAA considers that an adequate description of the unsafe condition has already been presented in the Notice of Proposed Rulemaking (NPRM). The FAA has determined that operation of the airplane with power levers positioned below the flight idle stop during flight could result in engine overspeed, possible engine damage or failure, and consequent reduced controllability of the airplane. Since the FAA has received reports of those types of incidents occurring on Model DHC-8 series airplanes, the FAA has determined that such an unsafe condition exists in those models.

Regardless of whether in-flight operation in beta resulted from intentional or unintentional pilot actions, the purpose of this AD is to prevent such operation. The FAA considers a requirement to install beta lockout to be the most effective means to achieve that objective.

12. Request to Ensure Consistent Requirements

One commenter points out that the design of the power lever system on Model DHC-8 series airplanes is different than that of other turbopropeller-powered airplanes that are addressed by AD's similar to the proposal. Several commenters assert that there seems to be different requirements for certain similar airplanes and similar requirements for different airplanes. The commenters request that the FAA “level the playing field” to ensure requirements are consistent for all airplane models.

The FAA acknowledges that there are different requirements for certain airplane models. As discussed previously, the requirements for different airplanes are based on certain aspects of design and service history of each different airplane model. Therefore, the FAA considers that the “playing field is level” in that the basic requirements for airplanes with similar design and service histories are equivalent.

13. Request for a Public Meeting

One commenter requests that a public meeting be held to discuss the proposed rule. The commenter states that the proposed beta lockout system will not improve safety. The commenter contends that since the manufacturer, operators, and TCCA do not support the proposal, a public meeting should be held to determine the most appropriate action.

The FAA does not concur that a public meeting is necessary to discuss the final rule. A Notice of Proposed Public Meeting was published in the Federal Register, and that meeting took place on June 11 and 12, 1996. Draft design criteria that the FAA was considering for use in evaluating a beta lockout system were included in that notice. The public meeting was held for the purpose of soliciting and reviewing information from the public on what type of FAA action would be appropriate to prevent future occurrences of inflight beta operation on all turbopropeller-powered airplanes. Further, a 90-day comment period was specified in the NPRM to allow an adequate period of time for commenters to respond. The fact that the final rule has been revised in response to certain information supplied by the commenters demonstrates the success of this process. For those issues on which commenters continue to disagree with the FAA's conclusions, given the extensive public participation to date, it is unlikely that yet another public meeting would resolve the issues. Therefore, further delay of this AD is inappropriate.

Conclusion

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 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.

Cost Impact

The FAA estimates that 185 de Havilland Model DHC-8-100, and -200, and -300 series airplanes of U.S. registry will be affected by this AD, that it will take approximately 1 work hour per airplane to accomplish the installation of the placard, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the placard installation on U.S. operators is estimated to be $11,100, or $60 per airplane.

Since the manufacturer has not yet developed a specific system commensurate with the requirements of this AD, the FAA is unable to provide specific information as to the number of work hours or cost of parts that will be required to accomplish the installation. However, based on similar installations of such systems accomplished previously on other airplane models, the FAA can reasonably estimate that approximately 200 work hours per airplane will be necessary to accomplish the system installation. The FAA also estimates that required parts will cost approximately $12,000 per airplane. Based on these figures, the cost impact of the required system installation on U.S. operators is estimated to be $4,440,000, or $24,000 per airplane.

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted.

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.

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
• 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:

2000-02-13 de Havilland: Amendment 39-11531. Docket 98-NM-179-AD.

Applicability: All Model DHC-8-100, -200, and -300 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 (d) 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 positioning of the power levers below the flight idle stop during flight, which could cause engine overspeed, possible engine damage or failure, and consequent reduced controllability of the airplane, accomplish the following:

(a) Within 30 days after the effective date of this AD, install a placard in a prominent location on the instrument panel of the cockpit that states: “Positioning of the power levers below the flight idle stop during flight is prohibited. Such positioning may lead to loss of airplane control, or may result in an engine overspeed condition and consequent loss of engine power.”

(b) Within 2 years after the effective date of this AD, install a system that would prevent positioning the power levers below the flight idle stop during flight, in accordance with a method approved by the Manager, New York Aircraft Certification Office (ACO), FAA, Engine and Propeller Directorate. Following accomplishment of that installation, the placard required by paragraph (a) of this AD may be removed.

(c) In the event that the system required by paragraph (b) of this AD malfunctions, or if the use of an override (if installed) is necessary, the airplane may be operated for three days to a location where required maintenance/repair can be performed, provided the system required by paragraph (b) of this AD has been properly deactivated and placarded for flightcrew awareness, in accordance with the FAA-approved Master Minimum Equipment List (MMEL).

(d) 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, New York ACO. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, New York ACO.

Note 2:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the New York ACO.

(e) 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.

(f) This amendment becomes effective on March 1, 2000.

Issued in Renton, Washington, on January 20, 2000.

Donald L. Riggin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.