[Federal Register Volume 64, Number 193 (Wednesday, October 6, 1999)]
[Proposed Rules]
[Pages 54234-54237]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-25920]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-CE-27-AD]
RIN 2120-AA64


Airworthiness Directives; REVO, Incorporated Models Lake LA-4, 
Lake LA-4A, Lake LA-4P, Lake LA-4-200, and Lake Model 250 Airplanes

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 REVO, Incorporated (REVO) Models Lake 
LA-4, Lake LA-4A, Lake LA-4P, Lake LA-4-200, and Lake Model 250 
airplanes. The proposed AD would require inspecting the left and right 
wing upper and lower spar caps and doublers for cracks, replacing any 
cracked parts and/or incorporating a modification kit depending on the 
extent of the damage, and reporting the results of the inspection to 
the Federal Aviation Administration (FAA). The proposed AD is the 
result of a report of a fatigue crack found at the second most inboard 
wing attachment bolt hole on one of the affected airplanes. Similar 
fatigue cracking has since been reported on seven more of the affected 
airplanes. The actions specified by the proposed AD are intended to 
detect and correct cracks in the wing spar caps and doublers, which 
could result in loss of the wing with consequent loss of control of the 
airplane.

DATES: Comments must be received on or before December 14, 1999.

ADDRESSES: Submit comments in triplicate to the FAA, Central Region, 
Office of the Regional Counsel, Attention: Rules Docket No. 99-CE-27-
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 REVO, Incorporated, P.O. Box 312, One High Street, Sanford, Maine 
04073. This information also may be examined at the Rules Docket at the 
address above.

FOR FURTHER INFORMATION CONTACT: Mr. Richard B. Noll, Aerospace 
Engineer, FAA, Boston Aircraft Certification Office, 12 New England 
Executive Park, Burlington, Massachusetts 01803; telephone: (781) 238-
7160; facsimile: (781) 238-7199.

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. 99-CE-27-AD.'' The

[[Page 54235]]

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-27-AD, Room 1558, 601 E. 12th Street, Kansas 
City, Missouri 64106.

Discussion

    The FAA has received a report of fatigue cracks that were found at 
the second-most inboard wing attachment bolt hole on a REVO Lake Model 
250 airplane. The cracks were detected during wing repair where the 
wing spar and wing skin were disassembled. Further analysis indicated 
that the cracks initiated at a machined notch at the flange termination 
point of the spar cap.
    The REVO Models Lake LA-4, Lake LA-4A, Lake LA-4P, and Lake LA-4-
200 airplanes are of the same type design as the Lake Model 250 
airplanes. Similar fatigue cracking to that of the above-referenced 
report has been found on seven more of these airplanes.
    This condition, if not detected and corrected in a timely manner, 
could result in loss of the wing with consequent loss of control of the 
airplane.

Relevant Service Information

    REVO has issued Service Bulletin B-79, dated June 12, 1999, which 
specifies procedures for accomplishing the following on the REVO Models 
Lake LA-4, Lake LA-4A, Lake LA-4P, Lake LA-4-200, and Lake Model 250 
airplanes:
--Inspecting the upper and lower wing spar doublers for fatigue cracks 
and corrosion;
--Inspecting the upper and lower wing spar cap angles for fatigue 
cracks and corrosion;
--Repairing or replacing any cracked or corroded parts or areas, as 
applicable; and
--Incorporating Aerofab B-79 kit on the wing spars.

The FAA's Determination

    After examining the circumstances and reviewing all available 
information related to the incidents described above, the FAA has 
determined that AD action should be taken to detect and correct cracks 
in the wing spar caps and doublers, which could result in loss of the 
wing with consequent loss of control of the airplane.

Explanation of the Provisions of the Proposed AD

    Since an unsafe condition has been identified that is likely to 
exist or develop in other REVO Models Lake LA-4, Lake LA-4A, Lake LA-
4P, Lake LA-4-200, and Lake Model 250 airplanes of the same type 
design, the FAA is proposing AD action. The proposed AD would require 
inspecting the left and right wing upper and lower spar caps and 
doublers for cracks, replacing any cracked parts and/or incorporating a 
modification kit depending on the extent of the damage, and reporting 
the results of the inspection to the FAA.
    Accomplishment of the proposed actions would be required in 
accordance with REVO Service Bulletin B-79, dated June 12, 1999.

Cost Impact

    The FAA estimates that 641 airplanes in the U.S. registry would be 
affected by the actions specified in the proposed AD.
    Wing removal and reinstallation to perform the proposed inspection 
would take approximately 32 workhours and the proposed inspection 
itself would take approximately 8 workhours per airplane. The average 
labor rate is approximately $60 an hour. Based on these figures, the 
total cost impact of the proposed inspection, including wing removal 
and reinstallation, on U.S. operators is estimated to be $1,538,400, or 
$2,400 per airplane.
    The incorporation of the modification kit proposed in this action 
would take approximately 12 workhours (6 hours per wing) to accomplish 
at an average labor rate of $60 per hour. The modification kit costs 
$2,000 for Model Lake 250 airplanes and $1,600 for Models Lake LA-4 and 
Lake LA-4-200 airplanes (average of $1,800 for cost impact 
considerations). Based on these figures, the total cost impact of the 
proposed modification on U.S. operators is estimated to be $1,615,320, 
or $2,520 per airplane.
    These figures do not take into account the costs of any part 
replacements that would be necessary if the FAA adopted the proposed 
rule. The FAA has no way of determining whether part replacements would 
be necessary for any affected airplane.

Compliance Time of the Proposed AD

    The compliance time of the proposed AD is presented in both hours 
time-in-service (TIS) and calendar time with the prevalent one being 
that which occurs first. The reason for this is that the fatigue cracks 
on the affected airplanes may have already initiated and could be 
further developing on the low-usage airplanes as well as high-usage 
airplanes. Utilizing the dual compliance times would assure that cracks 
in the wing spars would be detected on all affected airplanes in a 
timely manner without inadvertently grounding any of the affected 
airplanes.

Differences Between the Proposed AD and the Relevant Service 
Information

    REVO Service Bulletin B-79, dated June 12, 1999, specifies an 
inspection of the spar caps and angles for corrosion, as well as for 
fatigue cracks. After analyzing all service history and information 
related to this subject, the FAA has determined that the fatigue cracks 
that are developing in the spar cap angle are not associated with 
corrosion. Therefore, the proposed inspection in this AD only 
incorporates the fatigue crack specifications and does not include the 
corrosion specifications.

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 54236]]

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:

REVO, Incorporated: Docket No. 99-CE-27-AD.

    Applicability: The model and serial numbers airplanes, 
certificated in any category, that are listed in the following chart 
and incorporate any of the wing spar part numbers (or FAA-approved 
equivalent part numbers) that are in the chart below the airplane 
models and serial numbers:

                           Affected Airplanes
------------------------------------------------------------------------
                   Model                             Serial Nos.
------------------------------------------------------------------------
Lake LA-4.................................  246 through 421, 423 through
                                             429, 445, and 446.
Lake LA-4A................................  244 and 245.
Lake LA-4P................................  121.
Lake LA-4-200.............................  422, 430 through 444, and
                                             all serial numbers after
                                             446.
Lake Model 250............................  1 through 232.
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                   Wing Spar Part Numbers Incorporated
------------------------------------------------------------------------
              Wing spar parts                         Part Nos.
------------------------------------------------------------------------
Upper Spar Cap Angles.....................  2-1610-015 and 2-1610-016.
Lower Spar Cap Angles.....................  2-1610-075 and 2-1610-076.
Upper Spar Doublers.......................  2-1610-061 and 2-1610-081
                                             and 2-1610-065.
Lower Spar Doublers.......................  2-1610-063 and 2-1610-083.
------------------------------------------------------------------------

    Note 1: Improved design spar cap angles and the doubler kit 
referenced in this AD were incorporated at manufacture on the Lake 
Model 250 airplanes beginning with serial number 233. This AD does 
not apply to those airplanes.

    Note 2: 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 (h) 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 follows, unless already accomplished:

Inspections Required by Paragraph (a) of This AD

    At whichever of the following that occurs first:
    Upon the accumulation of 500 hours time-in-service (TIS) on the 
wing spars or within the next 50 hours TIS after the effective date 
of this AD, whichever occurs later; or
    Upon the accumulation of 500 hours TIS on the wing spars or 
within the next 12 calendar months after the effective date of this 
AD, whichever occurs later.

Repair, Replacement, and Kit Incorporation Required by Paragraphs (b), 
(c), and (d) of This AD

    Prior to further flight after the inspection required by 
paragraph (a) of this AD.
    To detect and correct cracks in the wing spar caps and doublers, 
which could result in loss of the wing with consequent loss of 
control of the airplane, accomplish the following:

    Note 3: The paragraph structure of this AD is as follows:
    Level 1: (a), (b), (c), etc.
    Level 2: (1), (2), (3), etc.
    Level 3: (i), (ii), (iii), etc.

    Level 2 and Level 3 structures are designations of the Level 1 
paragraph they immediately follow.
    (a) At the time specified in the Inspections Required by 
Paragraph (a) of this AD portion of the Compliance section of this 
AD, accomplish the following in accordance with the Inspection 
section of Service Bulletin B-79, dated June 12, 1999:
    (1) Remove the wings in accordance with the applicable 
maintenance manual. This procedure is part of the service bulletin, 
but is repeated in the AD to assure that the inspections are not 
accomplished before removing the wings.
    (2) Inspect the upper and lower wing spar doublers for fatigue 
cracks from the root end to outboard of the wing attachment fitting 
bolt holes, using solvent-removable fluorescent dye with a high 
sensitivity (Type I, Method C, Sensitivity Level 3), in accordance 
with ASTM E 165-95 and E 1417-95a or SAE 2647; and
    (3) Inspect the upper and lower wing spar cap angles for fatigue 
cracks from the root end to outboard of the wing attachment fitting 
bolt holes, using solvent-removable fluorescent dye with a high 
sensitivity (Type I, Method C, Sensitivity Level 3), in accordance 
with ASTM E 165-95 and E 1417-95a or SAE 2647. Cracks have been 
found in the cutout radius of the vertical flange near the second 
outboard hole.
    (b) If any crack(s) is(are) found in any spar doubler during any 
inspection required by this AD, prior to further flight, replace the 
spar doubler with a new part of the same part number, in accordance 
with the applicable maintenance manual.
    (c) If more than one crack is found in any spar cap angle, prior 
to further flight, accomplish both (1) and (2) below:
    (1) Replace any applicable spar cap angle with one of the 
following spar cap angles in accordance with the applicable 
maintenance manual:
    (i) Upper Spar Cap Angles: P/N 2-1610-087 and P/N 2-1610-088; 
and
    (ii) Lower Spar Cap Angles: P/N 2-1610-089 and 2-1610-091.
    (2) Incorporate Aerofab B-79 kit in accordance with the Kit 
section of Service Bulletin B-79, dated June 12, 1999. This kit 
incorporates the following parts:
    (i) Upper Spar Doubler: P/N 2-1610-093
    (ii) Upper Spar Filler: P/N 2-1610-095
    (iii) Lower Spar Doubler: P/N 2-1610-101
    (iv) Lower Spar Fillers: P/N 2-1610-097 and P/N 2-1610-099
    (d) If no cracks are found in the spar cap angles or if only one 
crack is found in any spar cap angle (cracks have predominantly been 
found in the cutout radius near the second outboard hole) of any 
spar cap angle, prior to further flight, incorporate Aerofab B-79 
kit in accordance with the Kit section of Service Bulletin B-79, 
dated June 12, 1999.
    (e) After the effective date of this AD, no person may install a 
wing on any of the affected airplanes, unless one of the following 
exists:
    (1) The wing is new from the factory; or
    (2) The inspection, repair and replacement, and kit 
incorporation requirements of this AD have been accomplished at the 
time of installation.
    (f) At the applicable compliance time presented in paragraphs 
(f)(1) and (f)(2) of this AD, report all inspection results to the 
Manager, FAA, Boston Aircraft Certification Office, Boston Aircraft 
Certification Office (ACO), 12 New England Executive Park, 
Burlington, Massachusetts 01803. Use the form that is referenced as 
the ``Appendix to Docket No. 99-CE-27-AD'' to present the findings. 
Information collection requirements contained in this regulation 
have been approved by the Office of Management and Budget (OMB) 
under the provisions of the Paperwork Reduction Act of 1980 (44 
U.S.C. 3501 et seq.) and have been assigned OMB Control Number 2120-
0056.
    (1) Within 10 calendar days after accomplishing the inspection 
required by paragraph (a) of this AD; or
    (2) Within 10 calendar days after the effective date of this AD 
if the requirements of this AD have already been accomplished.

    Note 4: The following information is helpful in accomplishing 
this AD:
    Cracks, if present in the affected areas, typically run fore and 
aft across the vertical flange thickness at or near the intersection 
with the horizontal flange; and
    Although this AD does not have to be accompished at a REVO-
authorized repair facility, the equipment and jigs needed to 
accomplish parts replacement are available at REVO-authorized repair 
facilities.

    (g) 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.
    (h) An alternative method of compliance or adjustment of the 
compliance times that provides an equivalent level of safety may be

[[Page 54237]]

approved by the Manager, FAA, Boston Aircraft Certification Office 
(ACO), 12 New England Executive Park, Burlington, Massachusetts 
01803. The request shall be forwarded through an appropriate FAA 
Maintenance Inspector, who may add comments and then send it to the 
Manager, Boston ACO.

    Note 5: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Boston ACO.

    (i) All persons affected by this directive may obtain copies of 
the document referred to herein upon request to REVO, Incorporated, 
P.O. Box 312, One High Street, Sanford, Maine 04073; or may examine 
this document at the FAA, Central Region, Office of the Regional 
Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106.

Appendix to Docket No. 99-CE-27-AD Inspection Results Report

    Report the following information to: Manager, Boston Aircraft 
Certification Office, Engine and Propeller Directorate, Aircraft 
Certification Service, Federal Aviation Administration, 12 New 
England Executive Park, Burlington, MA 01803-5299, Fax: (781) 238-
7199.

Operator/Repair Station------------------------------------------------
Aircraft Model---------------------------------------------------------
Aircraft S/N-----------------------------------------------------------
Date of Inspection-----------------------------------------------------

    Identify Operational Use (Estimate):

Take-off/Landings:
    Water, % of Total ____
    Land, % of Total ____
Parking
    Water, % of Time ____
    Land, % of Time ____

    Note: Add additional pages for the following for each part 
inspected.
Part No.---------------------------------------------------------------

Inspection

Dye Penetrant:
    Pass ____
    Fail ____
    N/A ____

If a crack is found, indicate the approximate location on the part 
and the length of the crack in inches:
----------------------------------------------------------------------
----------------------------------------------------------------------
Part Time-In Service (TIS) (Hours):
    Estimated ____
    Actual ____
    Unknown ____
    At Retirement ____
Log Book entry for Part No. ______ , is(date) ______, at retirement 
hours ______.

    Issued in Kansas City, Missouri, on September 29, 1999.
Michael K. Dahl,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-25920 Filed 10-5-99; 8:45 am]
BILLING CODE 4910-13-U