Airworthiness Directives; de Havilland Model DHC-8 Series Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 93-NM-46-AD; Amendment 39-9098; AD 94-26-02]

Airworthiness Directives; de Havilland Model DHC-8 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 de Havilland Model DHC-8 series airplanes, that

requires repetitive inspections of the passenger service unit (PSU)

printed circuit boards and power supply connectors to detect corrosion

and evidence of overheating; repair or replacement of the circuit

boards or replacement of connectors, if necessary; and eventual

installation of a terminating modification. This amendment is prompted

by reports that certain PSU printed circuit boards and power supply

connectors have overheated in service. The actions specified by this AD

are intended to prevent overheating of the PSU printed circuit board

and power supply connectors, which could lead to a fire in the PSU.

DATES: Effective January 26, 1995. -

The incorporation by reference of certain publications listed in

the regulations is approved by the Director of the Federal Register as

of January 26, 1995.

ADDRESSES: The service information referenced in this AD may be

obtained from de Havilland, Inc., Garratt Boulevard, Downsview, Ontario

M3K 1Y5, Canada. This information 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, 181 South Franklin Avenue, Room 202, Valley Stream, New York;

or at the Office of the Federal Register, 800 North Capitol Street,

NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Michele Maurer, Aerospace Engineer,

Systems and Equipment Branch, ANE-173, FAA, Engine and Propeller

Directorate, New York Aircraft Certification Office, 181 South Franklin

Avenue, Room 202, Valley Stream, New York 11581; telephone (516) 791-

6428; fax (516) 791-9024.

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 certain de Havilland Model DHC-8

series airplanes was published as a supplemental notice of proposed

rulemaking (NPRM) in the Federal Register on April 29, 1994 (59 FR

22138). That action proposed to require repetitive inspections of the

passenger service unit (PSU) printed circuit boards and power supply

connectors to detect corrosion and evidence of overheating; repair or

replacement of the circuit boards or replacement of connectors, if

necessary; and eventual installation of a modification that would

terminate the required inspections. -

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 requests that the proposed requirement to submit

inspection results to de Havilland be deleted. The commenter states

that, since the proposed rule would require that a terminating action

be accomplished, and since de Havilland has been aware of the addressed

problem for several years, any data supplied to de Havilland through

inspection reports would not shed any new light on the problem. The FAA

concurs. Upon reconsideration of this proposed requirement, the FAA

considers the submission of reports to be unnecessary. Additionally, de

Havilland has advised the FAA that it foresees no future need to

receive such reports. Accordingly, the FAA has revised the final rule

by deleting the reporting requirement. -

This same commenter requests that the compliance time for the

proposed initial inspection be revised to account for new airplanes.

The commenter suggests that new airplanes should not be required to be

inspected for at least 12 months since new. In considering this

comment, the FAA has determined that the applicability of the final

rule must be revised to limit it only to airplanes having serial

numbers 3 through 369, inclusive. Airplanes having serial numbers

higher that 369 were delivered with the equivalent of Modification 8/

1950 (the terminating modification required by this AD) installed. In

light of this, a revision to the final rule to address ``new''

airplanes, as suggested by the commenter, is unnecessary since all of

the affected airplanes have accumulated more than 12 months since new.

-

The FAA has revised the applicability of the final rule to clarify

the specific part numbers of the subject PSU's installed on the

affected airplanes. -

As a result of recent communications with the Air Transport

Association (ATA) of America, the FAA has learned that, in general,

some operators may misunderstand the legal effect of AD's on airplanes

that are identified in the applicability provision of the AD, but that

have been altered or repaired in the area addressed by the AD. The FAA

points out that all airplanes identified in the applicability provision

of an AD are legally subject to the AD. If an airplane has been altered

or repaired in the affected area in such a way as to affect compliance

with the AD, the owner or operator is required to obtain FAA approval

for an alternative method of compliance with the AD, in accordance with

the paragraph of each AD that provides for such approvals. A note has

been added to this final rule to clarify this requirement. -

The FAA has recently reviewed the figures it has used over the past

several years in calculating the economic impact of AD activity. In

order to account for various inflationary costs in the airline

industry, the FAA has determined that it is necessary to increase the

labor rate used in these calculations from $55 per work hour to $60 per

work hour. The economic impact information, below, has been revised to

reflect this increase in the specified hourly labor rate. -

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 133 airplanes of U.S. registry will be

affected by this AD. -

The required inspections will take approximately 2 work hours per

airplane to accomplish, at an average labor rate of $60 per work hour.

Based on these figures, the total cost impact of the proposed

inspections on U.S. operators is estimated to be $15,960, or $120 per

airplane, per inspection. -

The required terminating modification will require approximately 3

work hours per PSU to accomplish, at an average labor cost of $60 per

work hour. Required parts would cost approximately $62 per PSU. Each

airplane is equipped with between 18 and 26 PSU's. Based on these

figures, the total cost impact of the proposed modification on U.S.

operators is estimated to be $242 per PSU, or between $4,356 and $6,292

per airplane. -

The total cost impact figures discussed above are based on

assumptions that no operator has yet accomplished any of the proposed

requirements of this AD action, and that no operator would accomplish

those actions in the future if this AD were not adopted. However, the

FAA has been advised that the initial inspection has already been

accomplished on approximately 22 airplanes; therefore the future

economic impact of this rule is reduced by at least $2,640.

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, 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.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new

airworthiness directive:

94-26-02 de Havilland, Inc.: Amendment 39-9098. Docket 93-NM-46-AD.

Applicability: Model DHC-8 series airplanes, serial numbers 003

through 369, inclusive; equipped with passenger service units (PSU)

have part numbers 10-1418-1 or -2, or 10-1081-1 through -8;

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 use the authority

provided in paragraph (c) to request approval from the FAA. This

approval may address either no action, if the current configuration

eliminates the unsafe condition; or different actions necessary to

address the unsafe condition described in this AD. Such a request

should include an assessment of the effect of the changed

configuration on the unsafe condition addressed by this AD. In no

case does the presence of any modification, alteration, or repair

remove any airplane from the applicability of this AD.

Compliance: Required as indicated, unless accomplished

previously.

To prevent overheating of the passenger service unit (PSU)

printed circuit board and power supply connectors, which could lead

to a fire in the PSU, accomplish the following:

(a) Within 300 hours time-in-service after the effective date of

this AD, or within 30 days after the effective date of this AD, or

within 12 months after any previous inspection conducted prior to

the effective date in accordance with this paragraph, whichever

occurs later: Conduct a visual inspection of all PSU printed circuit

boards and power supply connectors to detect corrosion and evidence

of overheating, in accordance with paragraph III. of de Havilland

Alert Service Bulletin S.B. A8-33-30, Revision `A', dated December

18, 1992.

Note 2: The overheat condition referred to in this paragraph is

the discoloration of the printed circuit board around the connector

interfaces, and not the light conformal coating discoloration

resulting from the normal operation of high current devices mounted

on the printed circuit board.

(1) If no corrosion or evidence of overheating is detected,

repeat the inspection at intervals not to exceed 12 months.

(2) If any corrosion or evidence of overheating of the PSU

printed circuit board is detected as a result of any inspection,

prior to further flight, either repair or replace the PSU printed

circuit board in accordance with the service bulletin. Thereafter,

repeat the inspection at intervals not to exceed 12 months.

(3) If any corrosion or evidence of overheating of the power

supply connectors is detected as a result of any inspection, prior

to further flight, replace the affected power supply connector in

accordance with the service bulletin. Thereafter, repeat the

inspection at intervals not to exceed 12 months.

(b) Within 24 months after the effective date of this AD,

install Modification 8/1950 in accordance with de Havilland Service

Bulletin S.B. 8-33-34, dated August 10, 1993. Installation of this

modification constitutes terminating action for the inspections

required by paragraph (a) of this AD.

(c) 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 Aircraft Certification

Office (ACO), FAA, Engine and Propeller Directorate. 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 3: Information concerning the existence of approved

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

obtained from the New York ACO.

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

Secs. 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.

(e) The inspections shall be done in accordance with de

Havilland Alert Service Bulletin S.B. A8-33-30, Revision `A', dated

December 18, 1992. The modification shall be done in accordance with

de Havilland Service Bulletin S.B. 8-33-34, dated August 10, 1993.

This incorporation by reference was approved by the Director of the

Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part

51. Copies may be obtained from de Havilland, Inc., Garratt

Boulevard, Downsview, Ontario M3K 1Y5, Canada. Copies may be

inspected at the FAA, Transport Airplane Directorate, 1601 Lind

Avenue, SW., Renton, Washington; or at the FAA, Engine and Propeller

Directorate, New York Aircraft Certification Office, 181 South

Franklin Avenue, Room 202, Valley Stream, New York; or at the Office

of the Federal Register, 800 North Capitol Street, NW., suite 700,

Washington, DC.

(f) This amendment becomes effective on January 26, 1995.

Issued in Renton, Washington, on December 12, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-30940 Filed 12-23-94; 8:45 am]

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