Airworthiness Directives; Fokker Model F28 Mark 0100 Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 93-NM-132-AD; Amendment 39-8854; AD 94-06-06]

Airworthiness Directives; Fokker Model F28 Mark 0100 Series

Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD),

applicable to certain Fokker Model F28 Mark 0100 series airplanes, that

requires certain maximum brake wear limits to be incorporated into the

FAA-approved maintenance inspection program. This amendment also

requires that the Airplane Flight Manual be revised to include certain

procedures concerning operations in the event of a rejected takeoff

(RTO). This amendment is prompted by an accident in which a transport

category airplane executed an RTO and was unable to stop on the runway

due to worn brakes; and the subsequent review of allowable brake wear

limits for all transport category airplanes. The actions specified by

this AD are intended to prevent the loss of brake effectiveness during

a high energy RTO.

EFFECTIVE DATE: April 13, 1994.

ADDRESSES: Information concerning this amendment may be obtained from

or examined at the Federal Aviation Administration (FAA), Transport

Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton,

Washington 98055-4056.

FOR FURTHER INFORMATION CONTACT: Mark Quam, Aerospace Engineer,

Standardization Branch, ANM-113, FAA, Transport Airplane Directorate,

1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206)

227-2145; fax (206) 227-1320.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal

Aviation Regulations to include an airworthiness directive (AD) that is

applicable to certain Fokker Model F28 Mark 0100 series airplanes was

published in the Federal Register on November 1, 1993 (58 FR 58307).

That action proposed to require that certain maximum brake wear limits

be incorporated into the FAA-approved maintenance inspection program;

and that the Airplane Flight Manual (AFM) be revised to include certain

procedures concerning operations in the event of a rejected takeoff

(RTO).

Interested persons have been afforded an opportunity to participate

in the making of this amendment. Due consideration has been given to

the comments received.

One commenter supports the proposal.

Another commenter, the Air Transport Association (ATA) of America,

questions the need for the proposed AD. This commenter is aware of the

FAA's efforts to review and determine allowable aircraft brake wear

limits, since those efforts prompted the issuance of a series of AD's,

applicable to U.S.-manufactured airplanes, to mandate maximum brake

wear limits. While those U.S.-manufactured airplanes were certified to

new brake criteria, the commenter points out that airplanes such as the

Fokker Model F28 Mark 0100, which were certified under the Joint

Airworthiness Regulations (JAR) criteria, are certified to worn brake

standards. In light of this, the commenter questions why the FAA

indicated that the proposed AD was prompted by the 1988 accident

involving worn brakes on a McDonnell Douglas Model DC-10 airplane. This

commenter states that U.S. operators of Fokker Model F28 Mark 0100

series airplanes, at the time of airplane delivery, implemented within

their maintenance programs the same worn brake criteria as proposed in

the notice; additionally, these operators' FAA-approved AFM's already

reflect this criteria. Therefore, this commenter argues that there is

no basis for adopting the proposed rule unless it can be shown that

U.S. operators cannot safely administer to certified brake wear

criteria within their approved maintenance programs.

The FAA does not concur with this commenter's suggestion that this

AD action is not appropriate. The accident involving the Model DC-10

was the primary reason prompting this AD and the previously-issued AD's

to mandate specific maximum brake wear limits on transport category

airplane. During the process of promulgating those AD's, the FAA became

aware that not all operators were following the manufacturer's

recommended brake wear limits. For example, in one case, three

different operators of the same model of airplane were found to be

observing three different maximum brake wear limits. Further, the FAA

is aware that, until recently, not all manufacturers had provided brake

wear limits that met the FAA criteria, e.g., landing distance

predicated upon single engine-out, maximum takeoff weight, and fully

worn brakes. The purpose of this AD is in no way an attempt to question

the ability of U.S. operators to safely administer to brake wear limits

criteria; its purpose is to establish what those brake wear limits are.

Several commenters request that the proposed rule be revised to

eliminate the requirement to replace the landing gear sliding member

after an RTO event. One of these commenters suggests that, instead of

requiring replacement, the proposed rule could require inspections of

the sliding member, using procedures that are currently included in the

Fokker F28 Mark 0100 Aircraft Maintenance Manual (AMM) 05-51-01. This

commenter states that similar inspection procedures exist for most

other commercial aircraft, and those procedures have proven to be a

safe and effective method of evaluating landing gears for the effects

of high brake heat. This commenter also suggests that additional

procedures could include inspection of the axles for evidence of

discolored or peeling paint with cadmium plating that is blistered,

wrinkled, or mottled (signs of cadmium melting and resolidifying).

Cadmium melts at 610 deg.F, which is very close to the tempering

temperature of ultra-high strength steels; therefore, if the cadmium is

not melted, it is unlikely that any heat damage has been done to the

steel sliding member axle. This commenter notes that this criteria has

been used for other aircraft, and this commenter plans to contact

Fokker to request that this type of inspection criteria be added to the

Fokker F28 Mark 0100 AMM. Further, another commenter states that, on

other aircraft models in its fleet, it regularly performs a visual

inspection of the pistons following an RTO to determine the amount of

heat that the piston has been subjected to; the degree of discoloration

of the paint on the axle and the amount of damage to the hydraulic

hoses are evidence of the amount of heat. This commenter also plans to

contact Fokker to request the inclusion of this inspection in the AMM.

The FAA does not concur with the suggestion to revise the proposed

rule, at least at this time. The FAA has queried Fokker directly about

the inspection procedures suggested by these commenters; however,

Fokker was not aware of any effective nondestructive inspection

technique that can be used to establish whether cadmium embrittlement

has taken place on the axle after an RTO. Fokker did indicate that it

is currently working with the manufacturer of the brakes to devise a

way to limit the exposure of the sliding member to heat from the

brakes, which in turn would limit the need to replace the sliding

member. Once an inspection or other procedure is developed that would

preclude the necessity of replacing the sliding member, the FAA would

consider further rulemaking on this issue. In the meantime, under the

provisions of paragraph (d) of the final rule, the FAA would consider

requests for the use of alternative methods of complying with this

rule, provided sufficient data are presented to justify such requests.

One commenter requests that the proposed entry in the maintenance

program [as specified in paragraph (b) of the proposal] and the

proposed entry in the AFM [as specified in paragraph (c) of the

proposal] be revised. This commenter states that calculations have

shown that only when ``flap 0'' is selected, there is a possibility to

reach an energy level that can cause the axle to overheat. Therefore,

those entries should include a statement that, during the RTO scenario,

the flaps would have to be at 0 degrees. The commenter suggests that

the wording of both entries be changed to read as follows:

``If flap 0 is selected, and if a takeoff is rejected at a speed

greater than 90 percent of * * *''

The FAA concurs and has revised paragraphs (b) and (c) of the final

rule accordingly.

This same commenter suggests that the AFM entry proposed in

paragraph (c) be reworded to include language that is more familiar to

pilots, who will be the primary users of this information in the

Limitations Section. Specifically, the commenter suggests that pilots

would be more familiar with the term ``V1'' (takeoff decision

speed) than with ``VMBE'' (maximum brake energy limit speed). The

commenter states that use of V1 as a reference is more appropriate

than VMBE in this context, as well, since it is more conservative

with respect to the axle overheat problem. Along this same line, the

commenter suggests that the AFM wording be revised to indicate that

``the rejected takeoff conditions should be reported to maintenance

personnel prior to the next takeoff'' and that ``further dispatch may

be affected.'' The FAA concurs with all of these suggestions and has

revised paragraph (c) of the final rule accordingly.

Note: If a pilot were to report a rejected takeoff event to

maintenance personnel and refer the V1 speed involved,

maintenance personnel can recalculate the V1 figure to a

VMBE figure by means of a graph incorporated into the AMM.

This commenter also suggests that proposed paragraph (b) be revised

to specify the part numbers of the main landing gears (MLG) equipped

with the sliding members that need to be replaced. Adding a reference

to the MLG part numbers would avoid any relationship between the

currently-installed Dowty MLG's and other brands of MLG's that are

expected to be certified and installed in the near future. The FAA

concurs with this suggestion and has revised paragraph (b) of the final

rule accordingly.

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 previously

described. 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 83 airplanes of U.S. registry and 2 U.S.

operators will be affected by this AD.

Although the rule requires the incorporation of maximum brake wear

limits into the FAA-approved maintenance inspection program, no other

specific additional action, inspection, or part replacement costs

relative to that requirement are involved; such actions are currently a

part of the normal maintenance program. However, it is estimated that

it will require 20 work hours, at an average labor rate of $55 per work

hour, for each operator to incorporate the brake wear limitations into

its FAA-approved maintenance inspection program. Based on these

figures, the total cost impact of that requirement on U.S. operators is

estimated to be $2,200, or $1,100 per operator.

Additionally, the FAA estimates that it will take approximately 1

work hour per airplane to accomplish the required AFM revision, and

that the average labor rate is $55 per work hour. Based on these

figures, the total cost impact of that requirement on U.S. operators is

estimated to be $4,565, or $55 per airplane.

The total 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.

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 14 CFR part

39 of the Federal Aviation Regulations 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.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new

airworthiness directive:

94-06-06 Fokker: Amendment 39-8854. Docket 93-NM-132-AD.

Applicability: Model F28 Mark 0100 series airplanes, equipped

with brake part numbers (P/N) identified in paragraph (a) of this

AD, certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent the loss of brake effectiveness during a rejected

takeoff, accomplish the following:

(a) Within 180 days after the effective date of this AD,

accomplish the requirements of paragraphs (a)(1) and (a)(2) of this

AD:

(1) Incorporate the maximum brake wear limits specified in the

following tables into the FAA-approved maintenance inspection

program and comply with these measurements thereafter.

Table 1.--Brake Manufacturer: Aircraft Braking Systems Corp. (ABS)

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Maximum settings--Non refurbished brakes

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Brake P/N Maximum wear pin Alternate wear

measurement (inch/mm) measurement (inch/mm)

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5008132-2-............ 1.85'' (47 mm)......... 4.00'' (101.6 mm)

5008132-3-............ 1.85'' (47 mm)......... 4.00'' (101.6 mm)

5008132-4-............ 2.10'' (53.3 mm)....... 4.25'' (107.9 mm)

5008132-5-............ 2.10'' (53.3 mm)....... 4.25'' (107.9 mm)

5008132-6-............ 2.10'' (53.3 mm)....... 4.25'' (107.9 mm)

5008132-7-............ 2.10'' (53.3 mm)....... 4.25'' (107.9 mm)

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Note 1: Measuring instructions for non refurbished brakes can be

found in the ABS Component Maintenance Manual with Illustrated Parts

List AP-652 (Fokker Manual No. 32-43-77) or in ABS Service Bulletin

Fo100-32-35. ABS Service Bulletin Fo100-32-35 does not contain

measurement information relative to brake P/Ns 5008132-2 and -3.

Table 2

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Maximum settings--Refurbished brakes

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Brake P/N Maximum wear-pin Alternate wear

measurement-(inch/mm)- measurement (inch/mm)

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5008132-2............. 1.85'' (47 mm)......... 4.00'' (101.6 mm)

5008132-3............. 1.85'' (47 mm)......... 4.00'' (101.6 mm)

5008132-4............. 2.20'' (55.9 mm)....... 4.35'' (110.5 mm)

5008132-5............. 2.20'' (55.9 mm)....... 4.35'' (110.5 mm)

5008132-6............. 2.20'' (55.9 mm)....... 4.35'' (110.5 mm)

5008132-7............. 2.20'' (55.9 mm)....... 4.35'' (110.5 mm)

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Note 2: Refurbished brakes will have ``R11-3'' etched on the

brake housing adjacent to the shuttle valve. -

Note 3: Measuring instructions for refurbished brakes can be

found in the ABS Component Maintenance Manual with Illustrated Parts

List AP-652 (Fokker Manual No. 32-43-77) or in ABS Service Bulletin

Fo100-32-38.

(2) Any brake using a heat stack kit with an ``R'' after the P/N

must use the wear pin length specified on the Airworthiness Tag that

accompanies each heat stack kit, and must not use the ``Alternate

Wear Measurement'' noted in Table 1 of this AD under ``Non-

Refurbished Brakes'' to determine the brake's maximum wear limit.

Any of these brakes that are worn more than the maximum wear limit

must be replaced, prior to further flight, with a brake that is

within the limits specified in Table 2 of this AD.

(b) Within 180 days after the effective date of this AD,

incorporate the following information into the FAA-approved

maintenance program:

``If flap 0 is selected; and if a takeoff is rejected at a speed

greater than 90 percent of the scheduled Maximum Brake Energy limit

speed (VMBE) for the applicable weight, altitude, temperature,

wind conditions, runway slope and brake configuration (if

applicable); and if any brake is worn to 90 percent or more of its

brake wear limit: The main landing gear sliding member (identified

with one of the following main landing gear part numbers: 201072011,

201072012, 201072013, 201072014, 201072015, or 201072016) should be

replaced with a serviceable sliding member in accordance with Fokker

Aircraft Maintenance Manual, section 32-11-08.

Note: Only the sliding member with a brake that is more than 90

percent worn has to be replaced.''

(c) Within 180 days after the effective date of this AD, revise

the Limitations Section of the FAA-approved AFM, by adding the

following information. This may be accomplished by inserting a copy

of this AD in the AFM.

``If flap 0 is selected, and if a takeoff is rejected at a speed

greater than 90 percent of the scheduled takeoff decision speed

(V1) for the applicable weight, altitude, temperature, wind

conditions, runway slope, and brake configuration (if applicable),

as specified in the FAA-approved AFM, report the rejected takeoff

conditions to maintenance prior to next takeoff. Dispatch may be

affected.''

(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, Standardization Branch, ANM-113,

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,

Standardization Branch, ANM-113.

Note 4: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the Standardization Branch, ANM-113.

(e) Special flight permits may be issued in accordance with

Federal Aviation Regulations (FAR) 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 April 13, 1994.

Issued in Renton, Washington, on March 7, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-5700 Filed 3-11-94; 8:45 am]

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