[Federal Register Volume 63, Number 50 (Monday, March 16, 1998)]
[Proposed Rules]
[Pages 12706-12708]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-6585]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-CE-129-AD]
RIN 2120-AA64


Airworthiness Directives; Stemme GmbH & Co. KG Models S10 and 
S10-V Sailplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes to adopt a new airworthiness directive 
(AD) that would apply to certain Stemme GmbH & Co. KG (Stemme) Models 
S10 and S10-V sailplanes. The proposed action would require replacing 
the fuel filter, inserting a revision to the Limitations Section of the 
airplane flight manual, and inspecting the engine valve shafts for 
brownish-black sticky residue. If a residue is found on the valve 
shafts, the proposed action would require cleaning the engine. The 
proposed AD is the

[[Page 12707]]

result of mandatory continuing airworthiness information (MCAI) issued 
by the airworthiness authority for Germany. The actions specified by 
the proposed AD are intended to prevent engine valve malfunction, 
which, if not corrected, could cause engine failure during flight and 
loss of control of the sailplane.

DATES: Comments must be received on or before April 17, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Central Region, Office of the Regional Counsel, 
Attention: Rules Docket No. 97-CE-129-AD, Room 1558, 601 E. 12th 
Street, Kansas City, Missouri 64106. Comments may be inspected at this 
location between 8 a.m. and 4 p.m., Monday through Friday, holidays 
excepted.
    Service information that applies to the proposed AD may be obtained 
from Stemme GmbH & Co. KG, Gustav-Meyer-Allee 25, D-13355 Berlin, 
Federal Republic of Germany. This information also may be examined at 
the Rules Docket at the address above.

FOR FURTHER INFORMATION CONTACT: Mr. Mike Kiesov, Aerospace Engineer, 
Small Airplane Directorate, Aircraft Certification Service, FAA, 1201 
Walnut, suite 900, Kansas City, Missouri 64106; telephone (816) 426-
6934; facsimile (816) 426-2169.

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 should 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 that summarizes 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 No. 97-CE-129-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, Central Region, Office of the Regional Counsel, Attention: 
Rules Docket No. 97-CE-129-AD, Room 1558, 601 E. 12th Street, Kansas 
City, Missouri 64106.

Discussion

    The Luftfahrt-Bundesamt (LBA), which is the airworthiness authority 
for Germany, recently notified the FAA that an unsafe condition may 
exist on certain Stemme Models S10 and S10-V sailplanes. The LBA 
reports engine failure on two of the affected sailplanes. The engine 
failures occurred on sailplanes that were found to have a brown sticky 
substance on the engine. This substance is brownish-black in color and 
ranges from a lacquer-like hardness to gum-like sticky in composition. 
The substance may be residue and build-up formed by foreign materials 
dissolved in the fuel. The composition of the residue is causing the 
intake valves to stick in the valve guides. Sticky deposits were also 
found in parts of the induction system on the inside walls of the 
intake manifolds, as well as on the throttle shaft.
    This condition, if not corrected, could result in engine failure 
during flight and loss of control of the sailplane.

Relevant Service Information

    Stemme has issued Service Bulletin (SB) No. A31-10-021, dated June 
28, 1995, which specifies inserting a revision to the Limitations 
Section in the airplane flight manual (AFM) restricting the type and 
grade of fuel to use in the sailplane engine; and, specifies procedures 
for replacing the fuel filter if contaminated, along with inspecting 
the engine for the sticky brown residue.
    Limbach Flugmotoren Technical Bulletin No. 47, dated June 28, 1995, 
specifies procedures for inspecting certain engine components for 
contamination, and cleaning the engine. These procedures are a follow-
on to those found in Stemme SB No. A31-10-021, when a sticky brown 
residue is found in the engine.
    The LBA classified these service bulletins as mandatory and issued 
German AD 95-273, dated July 11, 1995, in order to assure the continued 
airworthiness of these sailplanes in Germany.

The FAA's Determination

    This sailplane model is manufactured in Germany and is type 
certificated for operation in the United States under the provisions of 
Sec. 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the 
applicable bilateral airworthiness agreement. Pursuant to this 
bilateral airworthiness agreement, the LBA has kept the FAA informed of 
the situation described above.
    The FAA has examined the findings of the LBA, reviewed all 
available information, including the service information referenced 
above, and determined that AD action is necessary for products of this 
type design that are certificated for operation in the United States.

Explanation of the Provisions of the Proposed AD

    Since an unsafe condition has been identified that is likely to 
exist or develop in other Stemme Models S10 and S10-V sailplanes of the 
same type design registered in the United States, the proposed AD would 
require replacing the fuel filter if contaminated, inserting a revision 
to the Limitations Section of the airplane flight manual (AFM), and 
inspecting the engine valve shafts for brownish-black sticky residue. 
If a residue is found on the valve shafts, the proposed action would 
require cleaning the engine. Accomplishment of the proposed insertion, 
inspection, and cleaning would be in accordance with Stemme Service 
Bulletin No. A31-10-021, dated June 28, 1995, and Limbach Flugmotoren 
Technical Bulletin No. 47, dated June 28, 1995.

Cost Impact

    The FAA estimates that 9 sailplanes in the U.S. registry would be 
affected by the proposed AD, that it would take approximately 5 
workhours per sailplane to accomplish the proposed action, and that the 
average labor rate is approximately $60 an hour. Parts cost 
approximately $30 per sailplane. Based on these figures, the total cost 
impact of the proposed AD on U.S. operators is estimated to be $2,970, 
or $330 per sailplane.

Proposed Compliance Time

    The FAA is proposing a calendar compliance time instead of hours 
time-in-service (TIS) because the average monthly usage of the affected 
sailplanes varies throughout the fleet. For example, one owner may 
operate the sailplane 25 hours TIS in one week, while another operator 
may operate the sailplane 25

[[Page 12708]]

hours TIS in one year. The sticky residue builds up on the engine 
regardless of sailplane use. In order to assure that all of the 
affected sailplanes are in compliance within a reasonable amount of 
time, the FAA is proposing a compliance time of 30 days after the 
effective date of this AD to insert the AFM Limitations Section 
revision, and 60 days after the effective date of this AD to replace 
the fuel filter and inspect the engine.

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 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) 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 has been placed 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 a new airworthiness directive 
(AD) to read as follows:

Stemme GMBH & Co. KG: Docket No. 97-CE-129-AD.

    Applicability: Model S10 (serial numbers 10-12 through 10-60), 
and Model S10-V (serial numbers 14-002 through 14-022) and 
transformed Model S10-V (serial numbers 14-012M to 14-060M) 
sailplanes, certificated in any category.

    Note 1: This AD applies to each sailplane 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 sailplanes 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 in the body of this AD, unless 
already accomplished.
    To prevent engine valve malfunction, which, if not corrected, 
could cause engine failure during flight and loss of control of the 
sailplane, accomplish the following:
    (a) Within the next 30 days after the effective date of this AD, 
insert a revision in the Limitations Section 2.4.2.1, Fuel, of the 
airplane flight manual (AFM) that states: ``Only authorized fuel is 
AVGAS 100LL'' in accordance with the Instructions section of Stemme 
Service Bulletin (SB) Document No. A31-10-021, dated June 28, 1995.
    (b) Incorporating the revision to the Limitations Section of the 
AFM, as required by paragraph (a) of this AD, may be performed by 
the owner/operator holding at least a private pilot certificate as 
authorized by section 43.7 of the Federal Aviation Regulations (14 
CFR 43.7), and must be entered into the aircraft records showing 
compliance with this AD in accordance with section 43.9 of the 
Federal Aviation Regulations (14 CFR 43.9).
    (c) Within the next 60 days after the effective date of this AD, 
accomplish paragraphs (c)(1), (c)(2), and (c)(3) of this AD;
    (1) Inspect the fine fuel filter for the accumulation of chopped 
cotton fibers, and replace the filter if it is contaminated, prior 
to further flight, in accordance with the Instructions section of 
Stemme SB Document No. A31-10-021, dated June 28, 1995; and,
    (2) Inspect the engine in accordance with LIMBACH Flugmotoren 
Technical Bulletin No. 47, dated June 28, 1995.
    (3) If a brownish-black sticky residue is found on the engine, 
prior to further flight, disassemble and clean the engine in 
accordance with LIMBACH Flugmotoren Technical Bulletin No. 47, dated 
June 28, 1995.
    (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 sailplane to a location where 
the requirements of this AD can be accomplished.
    (e) An alternative method of compliance or adjustment of the 
compliance times that provides an equivalent level of safety may be 
approved by the Manager, Small Airplane Directorate, FAA, 1201 
Walnut, suite 900, Kansas City, Missouri 64106. The request shall be 
forwarded through an appropriate FAA Maintenance Inspector, who may 
add comments and then send it to the Manager, Small Airplane 
Directorate.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Manager, Small Airplane Directorate.

    (f) Questions or technical information related to Stemme Service 
Bulletin No. A31-10-021, dated June 28, 1995, and LIMBACH 
Flugmotoren Technical Bulletin No. 47, dated June 28, 1995, should 
be directed to Stemme GmbH & Co. KG, Gustav-Meyer-Allee 25, D-13355 
Berlin, Federal Republic of Germany. This service information may be 
examined at the FAA, Central Region, Office of the Regional Counsel, 
Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106.

    Note 3: The subject of this AD is addressed in German AD 95-273, 
dated July 11, 1995.

    Issued in Kansas City, Missouri, on March 9, 1998.
Michael Gallagher,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 98-6585 Filed 3-13-98; 8:45 am]
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