[Federal Register Volume 60, Number 74 (Tuesday, April 18, 1995)]
[Proposed Rules]
[Pages 19383-19385]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-9470]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 95-NM-29-AD]


Airworthiness Directives; Fokker Model F28 Mark 0100 Series 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to certain Fokker Model F28 Mark 0100 
series airplanes. This proposal would require a one-time operational 
test of the No. 1 pitot heating system, and repair or replacement of 
failed elements. This AD also would require modification of certain 
electrical wiring, and replacement of the pitot head and a certain 
relay. This proposal is prompted by reports indicating that the No. 1 
Air Data Computer (ADC #1) failed due to icing of the No. 1 pitot tube. 
The actions specified by the proposed AD are intended to prevent icing 
of the No. 1 pitot tube, which could result in failure of the No. 1 ADC 
or output of erroneous airspeed data to all on-side subsidiary systems 
including the Automatic Flight Control and Augmentation System (AFCAS).

DATES: Comments must be received by May 30, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 95-NM-29-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 Aircraft USA, Inc., 1199 North Fairfax Street, 
Alexandria, Virginia 22314. This information may be examined at the 
FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington.

[[Page 19384]] FOR FURTHER INFORMATION CONTACT: Timothy Dulin, 
Aerospace Engineer, Standardization Branch, ANM-113, FAA, Transport 
Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-
4056; telephone (206) 227-2141; fax (06) 227-1320.

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 95-NM-29-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. 95-NM-29-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The Rijksluchtvaartdienst (RLD), which is the airworthiness 
authority for the Netherlands, recently notified the FAA that an unsafe 
condition may exist on certain Fokker Model F28 Mark 0100 series 
airplanes. The RLD advises that it received reports indicating that the 
No. 1 Air Data Computer (ADC #1) failed on Model F28 Mark 0100 series 
airplanes. This failure resulted in the loss of the captain's airspeed 
indicator and malfunction alerts from all on-side subsidiary systems 
[i.e., Flight Control Computer (FCC #1), Auto Throttle (AT #1), Yaw 
Damper (YD #1) and Horizontal Stabilizer Trim (Stab Trim #1)]. 
Subsequent investigation revealed that one of two heating elements (the 
tube part) of the No. 1 pitot tube had failed, which resulted in icing 
of the tube. Because the electrical current level of a single 
functioning element (100W) was higher than the trigger level of the 
pitot heat fault alert (42W), the failure was not annunciated. In 
severe icing conditions, operation of a single element produces too 
little heat to prevent freezing of the pitot probe. If an undetected 
heating element failure does not lead to a failure of ADC #1, erroneous 
data could be supplied to those on-side subsidiary systems mentioned 
above. This may cause the Automatic Flight Control and Augmentation 
System (AFCAS) to generate control commands based on incorrect airspeed 
data. Icing of the No. 1 pitot heat system, if not corrected, could 
result in failure of the ADC #1 or lead to erroneous data being 
supplied to all on-side subsidiary systems.
    Fokker has issued Service Bulletin SBF100-30-015, Revision 2, dated 
January 25, 1995, which describes procedures for accomplishing an 
operational test of the No. 1 pitot heating system. The service 
bulletin also describes procedures for removal of the DC current-
sensing relay and replacement with two new DC current-sensing relays; 
the replacement of the pitot head with a new pitot head; and 
modification of certain electrical wiring of the pitot heating system. 
Accomplishment of this service bulletin will prevent the pitot head 
from accumulating ice due to failure of a heating element in the No. 1 
pitot tube. The RLD classified this service bulletin as mandatory and 
issued Netherlands airworthiness directive BLA 94-114(A), dated August 
5, 1994, 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, the proposed AD would require a one-time 
operational test of the No. 1 pitot heating system, and repair or 
replacement of failed elements. This AD also would require modification 
of certain electrical wiring, replacement of the pitot head with a new 
pitot head, and replacement of the single DC current-sensing relay with 
two new DC current sensing relays. Certain actions would be required to 
be accomplished in accordance with the service bulletin described 
previously. Repair or replacement of any failed elements would be 
required to be accomplished in accordance with the Aircraft Maintenance 
Manual.
    (For airplanes equipped with a Flight Warning System (FWS) speed 
comparator, data from ADC #1 is compared to data from ADC #2 throughout 
the flight envelope. For airplanes not equipped with a FWS speed 
comparator, data from ADC #1 is only compared to data from ADC #2 
during autoland and redundant operation of AFCAS. Since airplanes not 
equipped with a speed comparator have a greater exposure to a hazardous 
condition, a shorter compliance time is necessary.)
    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 included in this notice to clarify this long-standing requirement.
    The FAA estimates that 119 airplanes of U.S. registry would be 
affected by this proposed AD, that it would take approximately 29 work 
hours per airplane to accomplish the proposed actions, and that the 
average labor rate is $60 per work hour. Required parts would cost 
approximately $4,800 per airplane. Based on these figures, the total 
cost impact of the proposed AD on U.S. operators is estimated to be 
$778,260, or $6,540 per airplane.
    The total cost impact figure discussed above is based on 
assumptions that no [[Page 19385]] 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.
    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. 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:

Fokker: Docket 95-NM-29-AD.

    Applicability: Model F28 Mark 0100 series airplanes, as listed 
in Fokker Service Bulletin SBF100-30-015, Revision 2, dated January 
25, 1995; 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 icing of the No. 1 pitot tube, which could cause 
failure of the No. 1 Air Data Computer (ADC) or output of erroneous 
airspeed data to all on-side subsidiary systems including the 
Automatic Flight Control and Augmentation System (AFCAS), accomplish 
the following:
    (a) Within 30 days after the effective date of this AD, perform 
an operational test of the No. 1 pitot heating system, in accordance 
with Part 1 of the Accomplishment Instructions of Fokker Service 
Bulletin SBF100-30-015, Revision 2, dated January 25, 1995.
    (1) If the pitot heating system passes the operational test, 
accomplish the requirements of either paragraph (b)(1) or (b)(2) of 
this AD, as applicable, at the times specified.
    (2) If any pitot tube heating element is found to be 
inoperative, prior to further flight, repair or replace the failed 
element with a serviceable element, in accordance with Fokker 100 
Aircraft Maintenance Manual (AMM).
    (b) Replace the pitot head with a new pitot head, replace the 
single DC current-sensing relay with two new DC current sensing 
relays, and modify the electrical wiring, in accordance with Part 2 
or 3, as applicable, of the Accomplishment Instructions of Fokker 
Service Bulletin SBF100-30-015, Revision 2, dated January 25, 1995. 
Perform these actions at the time specified in either paragraph 
(b)(1) or (b)(2) of this AD, as applicable.
    (1) For airplanes that are not equipped with an Flight Warning 
System (FWS) speed comparator: Within 12 months or the next 3,000 
hours time-in-service after the effective date of this AD, whichever 
occurs first. Or
    (2) For airplanes that are equipped with an FWS speed 
comparator: Within 24 months or the next 6,000 hours time-in-service 
after the effective date of this AD, whichever occurs first.
    (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, 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 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Standardization Branch, ANM-113.

    (d) 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 April 12, 1995.
S.R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-9470 Filed 4-17-95; 8:45 am]
BILLING CODE 4910-13-U