[Federal Register Volume 63, Number 90 (Monday, May 11, 1998)]
[Proposed Rules]
[Pages 25787-25789]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-12383]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-CE-128-AD]
RIN 2120-AA64


Airworthiness Directives; Stemme GmbH & Co. KG Model 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) Model 
S10-V sailplanes. The proposed action would require replacing the 
propeller blade suspension forks with parts of improved design. The 
proposed AD is the 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 
propeller suspension fork failure caused by design deficiency, which, 
if not corrected, could result in loss of a propeller blade and loss of 
sailplane controllability.

DATES: Comments must be received on or before June 15, 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-128-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-128-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-128-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 S10-V sailplanes. The LBA reports one incident 
of a failure of the propeller blade suspension fork during flight, 
which caused loss of sailplane controllability. Investigation of this 
incident revealed that the thread end groove area of the propeller 
blade suspension fork does not have an adequate design. This inadequate 
design causes fatigue of the propeller blade suspension fork to the 
point of failure.
    This condition, if not corrected, could result in loss of the 
propeller blade

[[Page 25788]]

during flight and possible loss of sailplane controllability.

Relevant Service Information

    Stemme has issued Service Bulletin No. A31-10-020, Am-index: 02.a, 
dated October 7, 1996, which specifies procedures for replacing the 
propeller blade suspension fork, part number (P/N) 10AP-V08, distance 
ring, P/N 10AP-V05, and nut, P/N 10AP-V06, with a new propeller blade 
suspension fork of improved design, P/N A09-10AP-V08, a new distance 
ring of improved design, P/N A09-10AP-05, and a new nut of improved 
design, P/N A09-10AP-V06.
    The LBA classified this service bulletin as mandatory and issued 
German AD 95-177/2, dated January 30, 1997, 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 Model S10-V sailplanes of the same 
type design registered in the United States, the proposed AD would 
require replacing the propeller blade suspension fork, distance ring, 
and nut with parts of improved design. Accomplishment of the proposed 
installation would be in accordance with Stemme GmbH & Co. KG Service 
Bulletin No. A31-10-020, Am-index: 02.a, dated October 7, 1996.

Cost Impact

    The FAA estimates that 7 sailplanes in the U.S. registry would be 
affected by the proposed AD, that it would take 6 hours per sailplane 
to accomplish the proposed action, and that the average labor rate is 
approximately $60 an hour. Parts cost approximately $930 per sailplane. 
Based on these figures, the total cost impact of the proposed AD on 
U.S. operators is estimated to be $9,030.

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-128-AD.

    Applicability: Model S10-V sailplanes (serial numbers (S/N) 14-
002 through 14-026, and converted sailplanes S/N 4-003M through 14-
036M), 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 (c) 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 upon the accumulation of 100 hours total 
time-in-service (TIS) on the sailplane propeller or within the next 
10 hours TIS after the effective date of this AD, whichever occurs 
later, unless already accomplished.
    To prevent propeller suspension fork failure caused by design 
deficiency, which, if not corrected, could result in loss of a 
propeller blade and loss of sailplane controllability, accomplish 
the following:
    (a) Replace the propeller blade suspension fork, part number (P/
N) 10AP-V08 (or an FAA-approved equivalent P/N), with new P/N A09-
10AP-V08 (or an FAA-approved equivalent P/N), distance ring, P/N 
10AP-V05 (or an FAA-approved equivalent P/N), with new P/N A09-10AP-
V05 (or an FAA-approved equivalent P/N), and nut, P/N 10AP-V06 (or 
an FAA-approved equivalent P/N), with new P/N A09-10AP-V06 (or an 
FAA-approved equivalent part number) in accordance with Stemme GmbH 
& Co. KG Service Bulletin No. A31-10-020, Am-index: 02.a, dated 
October 7, 1996.
    (b) 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.
    (c) 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 Small Airplane Directorate.

    (d) Questions or technical information related to pages 3 and 4 
of Stemme GmbH & Co. KG Service Bulletin, Modification v.p. 
propeller/failure blade suspension, No. A31-10-020, Am-index: 02.a, 
dated October 7, 1996, 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 95-177/
2, dated January 30, 1997.


[[Page 25789]]


    Issued in Kansas City, Missouri, on May 4, 1998.
Marvin R. Nuss,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-12383 Filed 5-8-98; 8:45 am]
BILLING CODE 4910-13-U