[Federal Register Volume 62, Number 11 (Thursday, January 16, 1997)]
[Proposed Rules]
[Pages 2324-2327]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-1029]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-NM-269-AD]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to all Fokker Model F28 Mark 
0100 and 0070 series airplanes, that currently requires revising the 
Airplane Flight Manual (AFM) 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. That AD was 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. This 
action would require a new terminating modification for the existing 
AFM revisions. This action would also require a new AFM revision to 
inform the flightcrew that, under certain conditions, an ``EMER DC 
BUS'' warning on the multi-function display unit (MFDU) will occur, and 
to take appropriate corrective actions. The actions specified by the 
proposed AD are intended to prevent failures of the emergency DC/AC bus 
power supply, which could reduce the ability of the flightcrew to 
control the airplane.

DATES: Comments must be received by February 25, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-269-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except 
Federal holidays.
    The service information referenced in the proposed rule may be 
obtained from Fokker Service B.V., Technical Support Department, P.O. 
Box 75047, 1117 ZN

[[Page 2325]]

Schipol Airport, The Netherlands. This information may be examined at 
the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington.

FOR FURTHER INFORMATION CONTACT: Tim Dulin, Aerospace Engineer, 
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 
227-2141; fax (206) 227-1149.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed 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 above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this notice may be changed in 
light of the comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 96-NM-269-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules 
Docket No. 96-NM-269-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On October 4, 1995, the FAA issued AD 95-21-10, amendment 39-9396 
(60 FR 53110, October 12, 1995), applicable to all Fokker Model F28 
Mark 0100 and 0070 series airplanes. That AD requires revising the 
Abnormal and Normal Procedures Sections of the FAA-approved Airplane 
Flight Manual (AFM) 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. That action was 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 
requirements of that 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.
    In the preamble to AD 95-21-10, the FAA specified that the actions 
required by that AD were considered ``interim action'' and that the 
manufacturer was developing a modification to positively address the 
unsafe condition. The FAA indicated that it may consider further 
rulemaking once the modification was developed, approved, and 
available. The manufacturer now has developed such a modification, and 
the FAA has determined that further rulemaking action is necessary; 
this proposed AD follows from that determination.

Actions Since Issuance of Previous Rule

    Since the issuance of that AD, Fokker has issued Service Bulletin 
SBF100-24-032, dated September 12, 1996, which describes procedures for 
modification of the DC bus transfer system. For certain airplanes, the 
modification involves removal of diode CR3; replacement of the DC bus 1 
circuit breaker and TRU 3 circuit breaker of the DC emergency bus 
supply, and replacement of the essential circuit breaker of the AC bus 
supply. The modification also involves replacement of the two battery 
power contactors (BPC) with a single BPC and addition of a control 
relay to the DC emergency bus system. For all airplanes, the 
modification involves alteration of the wiring to detect a battery 
drain. The modification will improve the switching logic of the 
emergency DC bus. Accomplishment of this modification would eliminate 
the need for the AFM revisions required by AD 95-21-10.
    In addition, Fokker has developed procedural information, for 
inclusion in the Abnormal Procedures Section of the AFM for the 
affected airplanes, to inform the flightcrew that an ``EMER DC BUS'' 
warning on the multi-function display unit (MFDU) will occur when the 
emergency DC bus is transferred to battery power, and to take 
appropriate corrective actions.
    Accomplishment of the modification and the new AFM revision will 
positively address the unsafe condition identified as failures of the 
emergency DC/AC bus power supply, which could lead to loss of on-side 
displays, autopilot, pressure control, and all communications; this 
situation could reduce the ability of the flightcrew to control the 
airplane.
    The Rijksluchtvaartdienst (RLD), which is the airworthiness 
authority for the Netherlands, classified these service bulletins and 
the AFM revision as mandatory and issued Netherlands airworthiness 
directive (BLA) 1995-089/4 (A), dated September 30, 1996, in order to 
assure the continued airworthiness of these airplanes in the 
Netherlands.

FAA's Conclusions

    These airplanes 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 Proposed 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, the proposed AD would supersede AD 95-21-10. It 
would continue to require 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 corrective actions. However, the 
proposed AD also would require modification of the DC bus transfer 
system, which would terminate the existing requirements for the AFM 
revisions. The modification would be required to be accomplished in 
accordance with the service bulletin described previously.
    Following accomplishment of the modification, the proposed AD also 
would require revising the Abnormal Procedures Section of the AFM to 
inform the flightcrew that an ``EMER DC BUS'' warning on the multi-
function

[[Page 2326]]

display unit (MFDC) will occur when the emergency DC bus is transferred 
to battery power, and to take appropriate corrective actions.

Cost Impact

    There are approximately 132 Fokker Model F28 Mark 0100 and 0070 
series airplanes of U.S. registry that would be affected by this 
proposed AD.
    The actions that are currently required by AD 95-21-10, and 
retained in this proposed AD, would take approximately 1 work hour per 
airplane to accomplish, at an average labor rate of $60 per work hour. 
Based on these figures, the cost impact of the currently required 
actions on U.S. operators is estimated to be $7,920, or $60 per 
airplane.
    The modification of the DC bus transfer system that is proposed in 
this new AD would take approximately 17 (Part 1) or 5 (Part 2) work 
hours per airplane to accomplish, at an average labor rate of $60 per 
work hour. The cost of required parts could range from $160 to as much 
as $2,360 per airplane. Based on these figures, the cost impact of the 
modification proposed by this AD on U.S. operators is estimated to be 
between $460 and $3,380 per airplane.
    The AFM revision that is proposed in this new AD would take 
approximately 1 work hour per airplane to accomplish, at an average 
labor rate of $60 per work hour. Based on these figures, the cost 
impact of the AFM revision proposed by this AD on U.S. operators is 
estimated to be $7,920, or $60 per airplane.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the current or proposed 
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 proposed herein would 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 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this proposed 
regulation (1) is not a ``significant regulatory action'' under 
Executive Order 12866; (2) is not a ``significant rule'' under the DOT 
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 
and (3) if promulgated, 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 copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting 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.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
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.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing amendment 39-9396 (60 FR 
53110, October 12, 1995), and by adding a new airworthiness directive 
(AD), to read as follows:

Fokker: Docket 96-NM-269-AD. Supersedes AD 95-21-10, Amendment 39-
9396.

    Applicability: All Model F28 Mark 0100 and 0070 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 
otherwise 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 (g) 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 failures of the emergency DC/AC bus power supply, 
which could reduce the ability of the flightcrew to control the 
airplane, accomplish the following:

RESTATEMENT OF ACTIONS REQUIRED BY AD 95-21-10, AMENDMENT 39-9396

    Note 2: For Model F28 Mark 0070 series airplanes, on which the 
procedures specified in Fokker Service Bulletins SBF100-24-033 and 
SBF100-24-034 have been accomplished, the AFM revisions required by 
paragraphs (a), (b), and (c) of this AD may be removed from the AFM.
    Note 3: For Model F28 Mark 0100 series airplanes, on which the 
procedures specified in Fokker Service Bulletin SBF100-24-030 have 
not been accomplished, or on which the procedures specified in 
Fokker Service Bulletin SBF100-24-033 have been accomplished; the 
AFM revisions required by paragraphs (a), (b), and (c) of this AD 
may be removed from the AFM.
    (a) For all airplanes: Within 7 days after October 27, 1995 (the 
effective date of AD 95-21-10, amendment 39-9396), 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 electrical 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 October 27, 1995, 
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) 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 Model F28 
Mark 0100 series

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airplanes, in pre-SBF100-24-009 configuration or in post SBF100-24-
030 configuration: Within 7 days after October 27, 1995, revise the 
Abnormal 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 4--Abnormal Procedures

Add to Sub-section 4.04--Electrical Power

ERRATIC ELECTRICAL SYSTEM BEHAVIOR

    In case of 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''

NEW ACTIONS REQUIRED BY THIS AD

    (d) For Model F28 Mark 0070 and 0100 series airplanes, as listed 
in Fokker Service Bulletin SBF100-24-032, dated September 12, 1996: 
Within 12 months after the effective date of this AD, modify the DC 
bus transfer system in accordance with Fokker Service Bulletin 
SBF100-24-032, dated September 12, 1996. Prior to further flight 
following accomplishment of this modification, accomplish paragraph 
(e) of this AD.

    Note 4: For Fokker Model F28 Mark 0070 series airplanes, Fokker 
Service Bulletin SBF100-24-032 recommends prior or concurrent 
accomplishment of the procedures specified in Fokker Service 
Bulletin SBF100-24-034, dated October 17, 1995, or Revision 1, dated 
September 12, 1996 (which is currently required by AD 96-26-03, 
amendment 39-9866).
    (e) Revise the Abnormal 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 4--Abnormal Procedures

Sub-section 4.04.05--Electrical Power--Bus Equipment List

    Insert a marker {time}  in each Bus Equipment List table, at the 
top of the column marked: EMERGENCY--DC.
    Add the following note at the beginning of the affected sub-
section:

    Note: {time}  When an ``EMER DC BUS'' fault is presented on the 
multi-function display unit (MFDU), check whether the electric panel 
digital readouts are operative.
     If operative, the EMER DC bus is supplied from the 
battery chargers via the batteries for 90 minutes and all services 
connected to this bus will remain available. After this time period, 
batteries will start to discharge and the effects of an EMER DC BUS 
fault should then be expected.
     If inoperative, continue with the EMER DC BUS FAULT 
procedure.
    At the bottom of each succeeding page (Bus Equipment List table) 
of sub-section 4.04.05, make a clear reference to the note marked 
{time}  located at the beginning of sub-section 4.04.05.''
    (f) Accomplishment of the modification in accordance with 
paragraph (d) of this AD constitutes terminating action for the 
requirements of paragraphs (a), (b), and (c) of this AD. After the 
modification has been accomplished, the previously required AFM 
revision may be removed from the AFM.
    (g) 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, 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 5: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Standardization Branch, ANM-113.
    (h) 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.

    Issued in Renton, Washington, on January 9, 1997.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-1029 Filed 1-15-97; 8:45 am]
BILLING CODE 4910-13-U