[Federal Register Volume 60, Number 197 (Thursday, October 12, 1995)]
[Rules and Regulations]
[Pages 53110-53112]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-25160]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 95-NM-179-AD; Amendment 39-9396; AD 95-21-10]


Airworthiness Directives; Fokker Model F28 Mark 0100 and Model 
F28 Mark 0070 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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[[Page 53111]]


SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to all Fokker Model F28 Mark 0100 and Model F28 Mark 0070 
series airplanes. This action requires revising the Limitations Section 
of the Airplane Flight Manual to include information that will enable 
the flightcrew to identify failures of the emergency direct current 
(DC)/alternating current (AC) bus power supply and to take appropriate 
corrective actions. This amendment is prompted by one report indicating 
that a diode failed, which resulted in battery drain and loss of the 
emergency DC bus power supply; and another report indicating that the 
circuit breaker of the transformer rectifier unit No. 3 tripped, which 
resulted in the loss of the emergency DC/AC bus power supply. The 
actions specified in this AD are intended to ensure that the flightcrew 
is advised of the potential hazard related to failures of the emergency 
bus power supply, and the procedures necessary to address it.

DATES: Effective October 27, 1995.
    Comments for inclusion in the Rules Docket must be received on or 
before December 11, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 95-NM-179-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056.
    Information concerning this amendment may be obtained from or 
examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, 
SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT: Ruth Harder, Aerospace Engineer, 
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 
227-1721; fax (206) 227-1149.

SUPPLEMENTARY INFORMATION: 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 
0100 and Model F28 Mark 0070 series airplanes. The RLD advises that it 
has received a report that a diode failed on a Fokker Model F28 Mark 
0100 series airplane. The flightcrew had no indication of this failure 
until the battery voltage dropped below a certain value. The RLD also 
advises that it has received another similar report, but on a Fokker 
Model Mark 0070 series airplane, in which the circuit breaker of the 
transformer rectifier unit No. 3 of the emergency direct current (DC) 
bus supply tripped; this situation resulted in an oscillating behavior 
of the electrical relays, causing the failure of not only the systems 
powered by the emergency DC bus, but also of the systems powered by the 
emergency alternating current (AC) bus. The cause of these failures is 
unknown at this time.
    Failure of a diode in the emergency DC bus supply could result in a 
battery drain, and the loss of the emergency DC bus and the subsequent 
loss of all systems powered by it. If the circuit breaker of the 
transformer rectifier unit No. 3 of the emergency DC bus supply trips, 
the resultant oscillations of the electrical relays could result in 
loss of both the emergency DC bus and emergency AC bus; this situation 
could lead to loss of on-side displays, autopilot, pressure control, 
and all communications, which could reduce the ability of the 
flightcrew to control the airplane.
    Fokker has developed procedural information, for inclusion in the 
Airplane Flight Manual (AFM) of the affected airplanes, that will 
enable the flight crew to identify failures of the emergency DC/AC bus 
power supply and to take appropriate corrective actions. The RLD 
classified this AFM material as mandatory, and issued Dutch 
airworthiness directive BLA 1995-089/2 (A), dated September 29, 1995, 
in order to assure the continued airworthiness of these airplanes in 
the Netherlands.
    This airplane model is manufactured in the Netherlands and is 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.
    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 
flightcrew is advised of the potential hazard related to failures of 
the emergency DC/AC bus power supply, and the procedures necessary to 
address it. This AD requires revising the Abnormal and Normal 
Procedures sections of the FAA-approved AFM to include information that 
will enable the flightcrew to identify failures of the emergency DC/AC 
bus power supply and to take appropriate procedures necessary to 
address it.
    This is considered to be interim action. The manufacturer has 
advised it currently is developing a modification that will positively 
address the unsafe condition addressed by this AD. Once this 
modification is developed, approved, and available, the FAA may 
consider additional rulemaking.
    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-179-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 

[[Page 53112]]
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 USC 106(g), 40101, 40113, 44701.


Sec. 39.13  [Amended]

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

95-21-10  Fokker: Amendment 39-9396. Docket 95-NM-179-AD.

    Applicability: All Model F28 Mark 0070 and Model F28 Mark 0100 
series airplanes, certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To ensure that the flightcrew is advised of the potential hazard 
related to failures of the emergency direct current (DC)/alternating 
current (AC) bus power supply, and the procedures necessary to 
address it, accomplish the following:
    (a) For all airplanes: Within 7 days after the effective date of 
this AD, revise the Abnormal Procedures section of the FAA-approved 
Airplane Flight Manual (AFM) to include the following statement. 
This may be accomplished by inserting a copy of this AD in the AFM.

``Section 4--Abnormal Procedures Add to Sub-section 4.04--
Electrical Power

STANDBY ANNUNCIATOR PANEL RED AC SUPPLY LIGHT ``ON''

On overhead electric panel:
    GEN LOAD--CHECK
 If all generator loads are approximately zero:
    LOSS OF AC SUPPLY PROCEDURE--APPLY
 If not all generator loads are approximately zero:
    DC EMER BUS SUPPLY TRU3 CIRCUIT BREAKER--CHECK
 If circuit breaker has tripped:
    DC EMER BUS SUPPLY TRU3 CIRCUIT BREAKER--RESET
    --If reset is unsuccessful:
    L and R AUDIO--ALTN
    Anticipate the effects of an eventual EMER DC BUS failure, see 
EMER DC BUS FAULT procedure.
 If circuit breaker has not tripped:
    L and R AUDIO--ALTN
    Anticipate the effects of an eventual EMER DC BUS failure, see 
EMER DC BUS FAULT procedure.''

    (b) For all airplanes: Within 7 days after the effective date of 
this AD, revise the Normal Procedures section of the FAA-approved 
AFM to include the following statement. This may be accomplished by 
inserting a copy of this AD in the AFM.

``Section 5--Normal Procedures Insert in front of Sub-section 
5.01.01--Take-off

     After engine start, select the Standby Annunciator 
Panel (SAP) backup mode ON via the BACKUP p/b at the SAP.
     Keep the SAP in the backup mode for the whole duration 
of flight until engine shutdown.
     Monitor the SAP.

    Note: Failure conditions as presented on the SAP bypass the 
Flight Warning Computer (FWC) and are not subject to alert 
inhibition. Be aware that the red LG light on the SAP will 
illuminate in case one or both thrustlever(s) are below the minimum 
take-off position and the landing gear is not down.''

    (c) For all Model F28 Mark 0070 series airplanes; and for all 
Model F28 Mark 0100 in pre-SBF100-24-009 configuration or in post 
SBF100-24-030 configuration: Within 7 days after the effective date 
of this AD, revise the Abnormal Procedures section of the FAA-
approved Airplane Flight Manual (AFM) to include the following 
statement. This may be accomplished by inserting a copy of this AD 
in the AFM.

``Section 4--Abnormal Procedures Add to Sub-section 4.04--
Electrical Power

ERRATIC ELECTRICAL SYSTEM BEHAVIOR

    In case of a continuous rattling sound, caused by the fast 
switching of relays and accompanied by blanking or erratic behavior 
of the three displays on the electric panel:
    BATTERIES--SELECT MOMENTARILY OFF, THEN ON
    AFFECTED SYSTEMS--RESTORE IF REQD

If the red AC SUPPLY light on the SAP comes ON:
    SAP RED AC SUPPLY LIGHT `ON' PROCEDURE--APPLY''

    (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: 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 
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.
    (f) This amendment becomes effective on October 27, 1995.

    Issued in Renton, Washington, on October 4, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-25160 Filed 10-11-95; 8:45 am]
BILLING CODE 4910-13-U