Aircraft
Certification Service Washington, DC U.S. Department of Transportation Federal Aviation Administration
2024-02
April 4, 2024
This is information only. Recommendations
aren’t mandatory.
Introduction
This
Special Airworthiness Information Bulletin (SAIB) alerts all owners,
operators, maintenance technicians, and inspectors of Revo Incorporated
Model Colonial C-1, Colonial C-2, Lake LA-4, Lake LA-4A, Lake LA-4P,
Lake LA-4-200, Lake Model 250 (including those modified in accordance
with Supplemental Type Certificate (STC) SA469NE) and Lake 270 Turbo
Renegade (Model 250 with STC AS469NE as noted in TCDS 1A13 Note 8)
aircraft to potential cracks in the wing rear attach beam assembly and
hole-quality issues that have been identified in a significant number
of aircraft.
At this time, the airworthiness concern is not an unsafe condition that
would warrant airworthiness directive (AD) action under Title 14 of the
Code of Federal Regulations (14 CFR) part 39.
Background
Over the past 45 years, the Lake Amphibian Club (LAC) received
approximately 27 reports of cracks in the wing rear spar web that were
visible in the aft wheel well. In addition, there is one report of
elongated bolt holes in the wing to fuselage attach fittings.
Figure 1 shows a Lake LA4-200 Buccaneer looking aft into the left-hand
main landing gear (MLG) wheel well and shows the area where cracks are
occurring and the recommended inspection area. Figure 1 also shows the
inspection area and the accessibility to perform the recommended
inspections.
Figures 2 and 3 show cracks found on a Lake LA-4-200 Buccaneer Left
side rear attach beam assembly. The small holes shown in the web are
manufacturer holes presumably for part positioning during forming
processes.
The information in the SAIB was provided to us by LAC. The potential
effect on the aircraft’s strength is prompting the FAA to issue this
SAIB.
Recommendations
The FAA recommends owners and operators perform the following inspections:
Inspect all wing attach
hardware for corrosion, loose rivets, witness marks indicating movement
in the joint and bolt, torque, and condition. Note that the bolts may
need to be loosened or removed to determine if gaps exist.
Inspect all wing attach fittings for security, wear, corrosion, damage, and condition of sealant at fuselage.
Inspect wing aft beam
assembly for damage, distortion, corrosion, and general condition.
Perform close visual inspection around the lightning holes near the
large cut out in the aft web. Look for indications of cracking as shown
in the pictures above.
Inspect wing tips for general security and condition – rock wing fore and aft to check for looseness at wing attach points.
Report all inspection
findings using the FAA’s Service Difficulty Reporting (SDR) System Site
at https://sdrs.faa.gov/. When filing SDRs, please include as much
information as possible. For example, if the spar had been replaced, if
there are any shims or gaps, and any alterations that might affect the
durability of the spar. Alternatively, inspection findings may be
reported directly to the Lake Amphibian Club using the contact
information below.
If cracks, gaps, or
elongated holes are found, repair or replace parts in accordance with
the manufacturer’s instructions, or using other methods, techniques,
and practices acceptable to the Administrator provided in FAA Advisory
Circular AC 43.13-1B
The inspections above can be
performed during pre-flight, annual, or 100-hour inspections. The FAA
also recommends that the above inspections also be performed following
a water loop incident or accident, wing impact damage/incident or
accident, landing gear impact damage/incident or accident, or other
cases where the wing may have incurred greater than normal torsion
stresses applied to the rear attachment area.