[Federal Register Volume 64, Number 139 (Wednesday, July 21, 1999)]
[Proposed Rules]
[Pages 39100-39102]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-18630]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-CE-25-AD]
RIN 2120-AA64


Airworthiness Directives; Stemme GmbH & Co. KG Models S10-V and 
S10-VT 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 all Stemme GmbH & Co. KG (Stemme) Models S10-V 
and S10-VT sailplanes that incorporate a certain propeller blade 
suspension fork. The proposed AD would require repetitively exchanging 
(through the manufacturer) the propeller blade suspension fork for a 
propeller blade suspension fork that has passed X-ray crack testing 
requirements. 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 
detect and correct fractured propeller blade suspension forks, which 
could result in the loss of a propeller blade during flight with 
possible lateral imbalance and loss of thrust.

DATES: Comments must be received on or before August 30, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Central Region, Office of the Regional Counsel, 
Attention: Rules Docket No. 99-CE-25-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, 
Germany; telephone: 49.33.41.31.11.70; facsimile: 49.33.41.31.11.73. 
This information also may be examined at the Rules Docket at the 
address above.

FOR FURTHER INFORMATION CONTACT: Mr. Mike Kiesov, Aerospace Engineer, 
FAA, Small Airplane Directorate, 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

[[Page 39101]]

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. 99-CE-25-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. 99-CE-25-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 all Stemme Models S10-V and S10-VT sailplanes. The LBA reports 
the loss of the propeller blade on one of the affected sailplanes 
during flight. Analysis of this propeller blade reveals a fracture 
located at the end of the threaded fastening pin.
    This condition, if not detected and corrected, could result in 
lateral imbalance and loss of thrust.

Relevant Service Information

    Stemme has issued Service Bulletin No. A31-10-051, Amendment 01.a, 
pages 3 and 4, dated March 6, 1999, which specifies repetitively 
exchanging (through the manufacturer) the propeller blade suspension 
fork for a propeller blade suspension fork that has passed X-ray crack 
testing requirements.
    The LBA classified this service bulletin as mandatory and issued 
German AD 1999-224, dated June 4, 1999, 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-V and S10-VT sailplanes of 
the same type design registered in the United States, the FAA is 
proposing AD action. The proposed AD would require repetitively 
exchanging (through the manufacturer) the part number (P/N) A09-10AP-
V08 (or FAA-approved equivalent part number) propeller blade suspension 
fork for one of these P/N forks that has passed X-ray crack testing 
requirements.

Relationship of the Proposed AD With AD 98-15-24

    AD 98-15-24, Amendment 39-10674 (63 FR 39484), requires replacing 
the P/N 10AP-V08 propeller blade suspension fork with a P/N A09-10AP-
V08 propeller blade suspension fork on Stemme Model S10-V sailplanes. 
The proposed AD is only written against those sailplanes with a P/N 
A09-10AP-V08 fork installed because the compliance time of the proposed 
AD is such that all affected sailplanes would have to comply with AD 
98-15-24 before the proposed AD (if followed with a final rule) would 
become effective. With this in mind, none of the affected sailplanes 
would have a P/N 10AP-V08 propeller blade suspension fork installed at 
the time the proposed AD would need to be complied with.
    Both the P/N A09-10AP-V08 and the P/N 10AP-V08 propeller blade 
suspension forks are part of the P/N 10AP-V08 propeller system 
configuration.

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 12 
workhours to remove and re-install the propeller blade suspension 
forks, and that the average labor rate is approximately $60 an hour. 
There is no cost to the operator to exchange the propeller blade 
suspension forks other than the labor costs. Based on these figures, 
the total cost impact of the proposed initial propeller blade 
suspension fork exchange on U.S. operators is estimated to be $6,480, 
or $720 per sailplane.
    These figures only take into the account the costs of the initial 
propeller blade suspension fork exchange and do not take into account 
the costs of any repetitive propeller blade suspension fork exchanges. 
The FAA has no way of determining the number of repetitive propeller 
blade exchanges each owner/operator would incur over the life of his/
her affected sailplane or until a terminating action is developed.

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.

[[Page 39102]]

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. 99-CE-25-AD.

    Applicability: Models S10-V and S10-VT sailplanes, all serial 
numbers, 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 as presented below:

--Initial Compliance: Upon accumulating 100 hours time-in-service 
(TIS) on a part number (P/N) A09-10AP-V08 (or FAA-approved 
equivalent part number) propeller blade suspension fork or within 
the next 10 hours TIS after the effective date of this AD, whichever 
occurs later, unless already accomplished; and
--Repetitive Compliance: Within 50 hours TIS after the initial 
compliance time and thereafter at intervals not to exceed 50 hours 
TIS.

    Note 2: AD 98-15-24, Amendment 39-10674 (63 FR 39484), requires 
replacing the P/N 10AP-V08 (or FAA-approved equivalent part number) 
propeller blade suspension fork with a P/N A09-10AP-V08 fork on 
Stemme Model S10-V sailplanes. This AD is only applies to those 
sailplanes with a P/N A09-10AP-V08 fork installed because the 
compliance time of this AD is such that all the Stemme Model S10-V 
sailplanes would have to comply with AD 98-15-24 before this AD 
becomes effective. Both the P/N A09-10AP-V08 and the P/N 10AP-V08 
propeller blade suspension forks are part of the P/N 10AP-V08 
propeller system configuration.

    To detect and correct fractured propeller blade suspension 
forks, which could result in the loss of a propeller blade during 
flight with possible lateral imbalance and loss of thrust, 
accomplish the following:
    (a) At the initial and repetitive compliance times, exchange 
(through the manufacturer) the propeller blade suspension fork for a 
P/N A09-10AP-V08 propeller blade suspension fork that has passed X-
ray crack testing requirements; and install the propeller blade 
suspension fork received from the manufacturer.

    Note 3: Stemme Service Bulletin No. A31-10-051, Amendment 01.a, 
pages 3 and 4, dated March 6, 1999, pertains to the subject matter 
of this AD.

    (b) Special flight permits may be issued in accordance with 
Secs. 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 
initial or repetitive 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 4: 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 Stemme Service 
Bulletin No. A31-10-051, Amendment 01.a, dated March 6, 1999, should 
be directed to Stemme GmbH & Co. KG, Gustav-Meyer-Allee 25, D-13355 
Berlin, Germany; telephone: 49.33.41.31.11.70; facsimile: 
49.33.41.31.11.73. 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 5: The subject of this AD is addressed in German AD 1999-
224, dated June 4, 1999.

    Issued in Kansas City, Missouri, on July 14, 1999.
Michael Gallagher,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 99-18630 Filed 7-20-99; 8:45 am]
BILLING CODE 4910-13-U