AD 86-20-04
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | STOL Aviation LLC | S-1B2 | Airworthiness Directives; ARCTIC AIRCRAFT COMPANY Model Interstate S-1B2 "Tern" Airplanes |
Unsafe Condition
Catastrophic flutter of the ailerons and/or elevators during flight at high speeds, resulting in possible loss of the airplane.
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Required Actions
Re-mark the airspeed indicator by removing the yellow arc from 142 mph to 160 mph and the red radial line at 160 mph, then marking a red radial line at 142 mph. Replace the Airplane Flight Manual with FAA-approved Revision 7 dated April 15, 1986, including applicable supplements. Remove existing seaplane speed placards and replace with the placard from Service Bulletin No. 5. Actions in (a) must be done at a certificated repair station with Class 1 instrument rating.
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Compliance Time
Within the next 100 hours time-in-service (TIS) or within 31 calendar days after the effective date of this AD, whichever comes first, unless already accomplished.
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Affected Aircraft
ARCTIC AIRCRAFT COMPANY Model Interstate S-1B2 'Tern' airplanes (Serial Numbers 1001 through 1029)
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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