[Federal Register Volume 61, Number 212 (Thursday, October 31, 1996)]
[Proposed Rules]
[Pages 56170-56172]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-27924]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 96-NM-32-AD]


Airworthiness Directives; Fokker Model F27 Mark 050, 100, 200, 
300, 400, 600, and 700 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 F27 Mark 050, 
100, 200, 300, 400, 600, and 700 series airplanes. This proposal would 
require an ultrasonic inspection to determine if certain tubes are 
installed in the drag stay units of the main landing gear (MLG), and 
various follow-on actions. This proposal is prompted by a report that, 
due to fatigue cracking from an improperly machined radius of the inner 
tube, a drag stay broke, and, consequently, lead to the collapse of the 
MLG during landing. The actions specified by the proposed AD are 
intended to prevent such fatigue cracking, which could result in 
reduced structural integrity or collapse of the MLG.

DATES: Comments must be received by December 10, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-32-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; and Dowty Aerospace, Customer Support 
Center, P.O. Box 49, Sterling,

[[Page 56171]]

VA 20166. This information may be examined at the FAA, Transport 
Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT: Ruth E. 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:

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-32-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-32-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 F27 Mark 050, 100, 200, 
300, 400, 600, and 700 series airplanes. The RLD advises that it has 
received a report that, due to a broken drag stay, the main landing 
gear (MLG) on one airplane collapsed during landing. The broken drag 
stay is attributed to fatigue cracking, which originated at a change in 
the cross-section of the inner tube. The apparent cause of such fatigue 
cracking has been attributed to an improperly machined radius of the 
inner tube of the drag stay. Such fatigue cracking, if not detected and 
corrected in a timely manner, could result in reduced structural 
integrity or collapse of the MLG.

Explanation of Relevant Service Information

    Fokker has issued Service Bulletin SBF50-32-029, dated February 11, 
1994 (for Model F27 Mark 050 series airplanes) and Service Bulletin 
F27/32-167, dated November 19, 1993 (for Model F27 Mark 100, 200, 300, 
400, 600, and 700 series airplanes). These service bulletins describe 
procedures for performing an ultrasonic inspection to determine if a 
tube having part number (P/N) 200485300 with a straight bore, or a tube 
having P/N 200259300 with a change in section (stepped bore), is 
installed in the drag stay units (DSU) of the main landing gear (MLG). 
They also describe procedures for various follow-on actions, including 
re-identification of certain tubes, replacement of certain DSU's with 
new/re-identified DSU's, and repetitive ultrasonic inspections of 
certain DSU's. The RLD classified these service bulletins as mandatory 
and issued Netherlands airworthiness directive BLA 93-169/2(A), dated 
April 29, 1994, in order to assure the continued airworthiness of these 
airplanes in the Netherlands.

FAA's Conclusions

    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.

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, the 
proposed AD would require an ultrasonic inspection to determine if 
certain tubes are installed on the DSU's of the MLG, and various 
follow-on actions. The actions would be required to be accomplished in 
accordance with the service bulletins described previously.

Cost Impact

    The FAA estimates that 10 Model F27 Mark 050, 100, 200, 300, 400, 
600, and 700 series airplanes of U.S. registry would be affected by 
this proposed AD, that it would take approximately 2 work hours per 
airplane to accomplish the proposed inspection, and that the average 
labor rate is $60 per work hour. Based on these figures, the cost 
impact of the inspection proposed by this AD on U.S. operators is 
estimated to be $1,200, or $120 per airplane.
    There currently are no Fokker Model F27 Mark 050 series airplanes 
on the U.S. Register that would require the inspection of the DSU. The 
only airplanes that would require this inspection are currently 
operated by non-U.S. operators under foreign registry; therefore, they 
are not directly affected by this AD action. However, the FAA considers 
that inclusion of that requirement in this proposed rule is necessary 
to ensure that the unsafe condition is addressed in the event that any 
of these airplanes are imported and placed on the U.S. Register in the 
future.
    The cost impact figure discussed above is 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.

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

[[Page 56172]]

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 adding the following new 
airworthiness directive:

Fokker: Docket 96-NM-32-AD.

    Applicability: Model F27 Mark 050, 100, 200, 300, 400, 600, and 
700 series airplanes, equipped with Dowty Aerospace main landing 
gear (MLG) drag stay units (DSU) having part number (P/N) 200684001, 
200261001, or 200485001; 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 request approval for an 
alternative method of compliance in accordance with paragraph (e) 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 fatigue cracking in drag stay unit of the main 
landing gear (MLG), which could result in reduced structural 
integrity or collapse of the MLG, accomplish the following:
    (a) Within 60 days after the effective date of this AD, perform 
an ultrasonic inspection to determine if a tube having part number 
(P/N) 200485300 with a straight bore, or a tube having P/N 200259300 
with a change in section (stepped bore), is installed on the DSU's 
of the MLG, in accordance with Fokker Service Bulletin F27/32-167, 
dated November 19, 1993 (for Model F27 Mark 100, 200, 300, 400, 600, 
and 700 series airplanes), or Fokker Service Bulletin SBF50-32-029, 
dated February 11, 1994 (for Model F27 Mark 050 series airplanes), 
as applicable.

    Note 2: Fokker Service Bulletin F27/32-167 references Dowty 
Service Bulletins 23-169B and 32-82W; and Fokker Service Bulletin 
SBF50-32-029 references Dowty Service Bulletin F50-32-50; as 
additional sources of service information for procedures to 
accomplish the actions specified in this AD.

    (b) For all airplanes: If any tube having P/N 200485300 with a 
straight bore is found installed during the inspection required by 
paragraph (a) of this AD, prior to further flight, reidentify it in 
accordance with Fokker Service Bulletin F27/32-167, dated November 
19, 1993 (for Model F27 Mark 100, 200, 300, 400, 600, and 700 series 
airplanes); or Fokker Service Bulletin SBF50-32-029, dated February 
11, 1994 (for Model F27 Mark 050 series airplanes); as applicable.
    (c) For Model F27 Mark 50 series airplanes: If any tube having 
P/N 200259300 with a change in section (stepped bore) is found 
installed during the inspection required by paragraph (a) of this 
AD, prior to further flight, replace the DSU with a new or 
serviceable DSU having P/N 200684004, in accordance with Fokker 
Service Bulletin SBF50-32-029, dated February 11, 1994.
    (d) For F27 Mark 100, 200, 300, 400, 600, and 700 series 
airplanes: If any tube having P/N 200259300 with a change in section 
(stepped bore) is found installed during the inspection required by 
paragraph (a) of this AD, prior to further flight, re-identify the 
DSU in accordance with Fokker Service Bulletin F27/32-167, dated 
November 19, 1993. Following accomplishment of the re-
identification, prior to further flight, perform an ultrasonic 
inspection to detect cracks in the re-identified DSU's, in 
accordance with that service bulletin.
    (1) For airplanes equipped with any DSU re-identified as P/N 
200684003, 200261003, or 200485003: If no crack is detected, no 
further action is required by this AD.
    (2) For airplanes equipped with any DSU re-identified as P/N 
200684002, 200261002, or 200485002: If no crack is detected, 
accomplish paragraph (c)(2)(i) and (c)(2)(ii) of this AD.
    (i) Repeat the ultrasonic inspection required by paragraph (d) 
of this AD thereafter at intervals not to exceed 1,500 flight 
cycles.
    (ii) At the next MLG overhaul, but no later than 12,000 flight 
cycles after the effective date of this AD, rework and re-identify 
the DSU again, or replace the DSU with a re-identified DSU, in 
accordance with the service bulletin. Accomplishment of the rework 
and re-identification, or replacement constitutes terminating action 
for the repetitive inspection requirements of this AD.
    (3) If any crack signal indication of any DSU tube is greater 
than or equal to 80 percent, prior to further flight, replace the 
DSU with a re-identified DSU, in accordance with the applicable 
service bulletin.
    (4) If any crack signal indication of any DSU tube is greater 
than or equal to 1 percent but less than 80 percent, accomplish 
paragraph (d)(4)(i) and (d)(4(ii) of this AD.
    (i) Repeat the ultrasonic inspection required by paragraph (d) 
of this AD thereafter at intervals not to exceed 1,500 flight 
cycles.
    (ii) At the next MLG overhaul, but no later than 12,000 flight 
cycles after the effective date of this AD, replace the DSU with a 
re-identified DSU, in accordance with the service bulletin. 
Accomplishment of the replacement constitutes terminating action for 
the repetitive inspection requirements of this AD.
    (e) 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 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Standardization Branch, ANM-113.

    (f) 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 October 24, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-27924 Filed 10-30-96; 8:45 am]
BILLING CODE 4910-13-U