[Federal Register Volume 62, Number 33 (Wednesday, February 19, 1997)]
[Proposed Rules]
[Pages 7373-7375]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-3961]
=======================================================================
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 96-CE-40-AD]
RIN 2120-AA64
Airworthiness Directives; Grob Luft-und Raumfahrt, GmbH; Models G
109 and G 109B Sailplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
-----------------------------------------------------------------------
SUMMARY: This document proposes to adopt a new airworthiness directive
(AD) that would apply to certain Grob Luft-und Raumfahrt (Grob) Models
G 109 and G 109B sailplanes. The proposed action would require
inspecting the landing gear retaining bars and landing gear legs for
proper radius, thickness, and cracking, and installing additional
supportive parts or replacing the retaining bars and landing legs with
parts of improved design. Reports of landing gear failure on certain G
109 and G 109B sailplanes prompted the proposed action. The actions
specified by the proposed AD are intended to prevent failure of the
landing gear legs and possible loss of the sailplane.
DATES: Comments must be received on or before April 21, 1997.
ADDRESSES: Submit comments on the proposal in triplicate to the Federal
Aviation Administration (FAA), Central Region, Office of the Assistant
Chief Counsel, Attention: Rules Docket No. 96-CE-40-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 Grob Luft-und Raumfahrt, GmbH., D-8939, Mattsies-am Flugplatz,
Germany. This information also may be examined at the Rules Docket at
the address above.
FOR FURTHER INFORMATION CONTACT: Mr. J. Mike Kiesov, Project Officer,
Sailplanes, FAA, Small Airplane Directorate, 1201 Walnut, suite 900,
Kansas City, Missouri 64106; telephone (816) 426-6932; 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. 96-CE-40-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 Assistant Chief Counsel,
Attention: Rules Docket No. 96-CE-40-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 Grob G 109 and G 109B sailplanes. The LBA reports that
the landing gear on three of these sailplanes failed during landing. An
investigation of these incidents revealed landing gear legs with
fatigue cracks and weak retaining bars from an error in the
manufacturing process. This condition, if not detected and corrected,
could result in landing gear failure and possible loss of the
sailplane.
Related Service Information
Grob has issued Service Bulletin TM 817-39, dated January 4, 1994,
which specifies procedures for inspecting and modifying or replacing
the landing gear retaining bars and the landing gear legs. The landing
gear retaining bar should have a minimum radius of 3.0 millimeters (mm)
on the chamfer. If the
[[Page 7374]]
radius is less than 3.0 mm, the retaining bar would be replaced with an
improved retaining bar (part number (P/N) 109-5000.02) and a plastic
reinforcing strip (P/N 109-5000.07). If the radius is 3.0 mm or
greater, the plastic reinforcing strip would be glued onto the
retaining bars.
The landing gear legs that are not marked with ``0'' (zero) would
require inspecting for cracks by the magnetic particle or x-ray method,
and if there are any cracks measuring greater than 0.5 mm, the landing
gear legs would be replaced with new legs. If there are cracks
measuring less than 0.5 mm, the proposed action would require polishing
the cracks out, unless polishing would reduce the total leg thickness
to less than 13.0 mm. If the leg thickness is less than 13.0 mm, the
landing gear leg would be replaced. If there are no cracks in the
landing gear legs, or the landing gear leg thickness is greater than
13.0 mm, after polishing, the proposed action would require
repetitively inspecting until cracks are found, or until new landing
gear legs are installed. Installing the improved landing gear legs and
the improved retaining bars would terminate the proposed repetitive
inspection.
The LBA classified this service bulletin as mandatory and issued AD
94-004/2 Grob, dated February 3, 1994, in order to ensure the continued
airworthiness of these sailplanes in Germany.
FAA's Determination
These sailplane models are manufactured in Germany and are 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 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 Grob G 109 and G 109B sailplanes of the same
type design registered in the United States, the proposed AD would
require:
(1) Inspecting the retaining bars chamfer for the correct radius,
and replacing the bars or reinforcing the bars, as applicable.
(2) Inspecting the landing gear legs that are not marked with ``0''
(zero) on the front of the legs for fatigue cracks, and if cracks are
greater than or less than the tolerance measurement, either replace or
repetitively inspect the landing gear legs, as applicable.
(3) Measure the total thickness of the landing gear legs. If they
measure less than, greater than or equal to 13.0 mm, continue to
inspect or replace legs with new improved legs, as applicable.
(4) Replacing the landing gear legs with parts of improved design
would terminate the proposed repetitive inspections.
Cost Impact
The FAA estimates that 63 sailplanes in the U.S. registry would be
affected by the proposed AD, that it would take approximately 2
workhours per leg per sailplane to accomplish the inspection and
modification on the proposed retaining bar action, approximately 9
workhours per leg per sailplane to accomplish the removal, inspection
and re-installation, and approximately 6 workhours per leg to
accomplish the replacement. The average labor rate is approximately $60
an hour. Parts cost approximately $90 per sailplane for retaining bars
and $1800 per sailplane for landing gear legs. The plastic strip for
the retaining bar is provided by the manufacturer at no charge.
Breaking these costs down by individual action, the estimated total
cost for each action would be as follows:
--The proposed inspection and modification of the retaining bars would
be $210 ($120/labor + $90/parts) per sailplane or $13,230 for the U.S.
fleet.
--The proposed inspection and polishing of the landing gear legs would
be $540 per sailplane or $34,020 for the U.S. fleet.
--The proposed replacement of the landing gear legs would be $2,160
($360/labor + $1,800/parts) per sailplane or $136,080 for the U.S.
fleet.
--The cost for the proposed repetitive inspections on the landing gear
legs is not included in the above figures.
The manufacturer has informed the FAA that they have dispatched
equipment to outfit approximately 30 sailplanes with new retaining
bars, reducing the estimated cost impact of the retaining bars from
$13,230 to $6,930. The manufacturer has also distributed approximately
3 sets of new landing gear legs, reducing the estimated total cost
impact of the landing gear leg replacement from $136,080 to $129,600.
Proposed Compliance Time
The compliance time of the proposed AD is presented in calendar
time instead of hours time-in-service (TIS). The FAA has determined
that a calendar time compliance is the most desirable method because
the unsafe condition of the landing gear legs described by this AD is
caused by corrosion. Corrosion initiates as a result of sailplane
operation, but can continue to develop regardless of whether the
sailplane is in service or in storage. Therefore, to ensure that the
above-referenced condition is detected and corrected on all sailplanes
within a reasonable period of time without inadvertently grounding any
sailplanes, a compliance schedule based upon calendar time instead of
hours TIS is required.
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:
[[Page 7375]]
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 USC 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:
Grob Luft-Und Raumfahrt, GMBH. (GROB): Docket No. 96-CE-40-AD.
Applicability: Models G 109 and G 109B 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 (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 failure of the landing gear legs and possible loss of
the sailplane, accomplish the following:
(a) Within the next 120 calendar days after the effective date
of this AD, inspect the retaining bars chamfer on both landing gear
legs for a minimum of 3.0 millimeters (mm) radius in accordance with
the ``Actions'' section, paragraph A3 in Grob Service Bulletin (SB)
817-39, dated January 4, 1994.
(1) If the chamfer radius is 3.0 mm or greater, prior to further
flight, glue a reinforcing plastic strip (part number (P/N) 109-
5000.07) to the retaining bar in accordance with the ``Actions''
section, paragraph A4 in Grob SB 817-39, dated January 4, 1994.
(2) If the chamfer radius is less than 3.0 mm, prior to further
flight, replace with a new improved retaining bar (P/N 109-5000.02),
and install the plastic strip (P/N 109-5000.07) in accordance with
the ``Actions'' section, paragraph A5 in Grob SB 817-39, dated
January 1994.
(b) For sailplanes not equipped with landing gear legs, P/N
109B-5001.01/1, within the next 2,000 sailplane landings or 1,000
hours TIS after the effective date, whichever occurs first, inspect
the landing gear legs for cracks (using the magnetic particle or X-
ray analysis method) in accordance with the ``Actions'' section,
paragraph B9 in Grob SB 817-39, dated January 4, 1994.
Note 2: Landing gear legs (P/N 109B-5001.01/1) have a ``0''
stamped on the front side of the leg for easy identification.
(1) If there are cracks less than or equal to 0.5 mm, prior to
further flight, polish the existing legs or replace the legs with P/
N 109B-5001.01/1 in accordance with the ``Actions'' section,
paragraph B10 in Grob SB 817-39, dated January 4, 1994.
(2) If the polished landing gear legs measures less than 13.0
mm, prior to further flight, replace the landing gear legs with P/N
1090B-5001.01/1 in accordance with the ``Actions'' section,
paragraph B10 in Grob SB 817-39, dated January 4, 1994.
(3) If no cracks are found, or the cracks are less than 0.5 mm,
and the thickness of the landing gear legs is equal to or greater
than 13.0 mm, repetitively inspect the landing gear legs for cracks
every 1,000 landings or 500 hours TIS, whichever occurs first, in
accordance with the ``Actions'' section, paragraph B12 in Grob SB
817-39, dated January 4, 1994.
(4) If during any of the repetitive inspections, the legs have
previously been polished and new cracks are found, prior to further
flight, replace the legs with P/N 109B-5001.01/1 in accordance with
the ``Actions'' section, paragraph B12 in Grob SB 817-39, dated
January 4, 1994.
(c) Replacement of the landing gear legs with P/N 109B-5000.01/1
terminates the repetitive inspections required by this AD and Grob
SB 817-39, dated January 4, 1994.
(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
initial or repetitive compliance times that provides an equivalent
level of safety may be approved by the Manager, Small Airplane
Directorate, 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 3: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Small Airplane Directorate.
(f) All persons affected by this directive may obtain copies of
the documents referred to herein upon request to Grob Luft-und
Raumfahrt, GmbH., D-8939, Mattsies-am Flugplatz, Germany or may
examine these documents at the FAA, Central Region, Office of the
Assistant Chief Counsel, Room 1558, 601 E. 12th Street, Kansas City,
Missouri 64106.
Issued in Kansas City, Missouri, on February 10, 1997.
Henry A. Armstrong,
Acting Manager, Small Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 97-3961 Filed 2-18-97; 8:45 am]
BILLING CODE 4910-13-U
