AD 99-04-07
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Saab AB, Saab Aerosystems | SAAB 340B | Airworthiness Directives; Saab Model SAAB SF340A and SAAB 340B Series Airplanes |
| aircraft | Saab AB, Saab Aerosystems | 340A (SAAB SF340A) | Airworthiness Directives; Saab Model SAAB SF340A and SAAB 340B Series Airplanes |
Unsafe Condition
Degraded bottom engine mounts, due to material degradation, change damping characteristics leading to excessive engine vibration, which could damage the nacelle structure, reduce structural integrity and fire shielding, cause chafing of the fire sensor loop leading to nuisance warnings and precautionary shutdowns, or damage the air pressure tube leading to engine failure.
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Required Actions
Review airplane maintenance records to identify the bottom engine vibration isolator, inspect the aft engine vibration isolator's deflection, replace the bottom isolator if chafing is found, repair discrepant parts, and inspect/replace side and aft isolators as needed. Follow SAAB service bulletin procedures with FAA/LFV-approved repairs for deflection issues.
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Compliance Time
Before further flight
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Affected Aircraft
Saab Model SAAB SF340A and SAAB 340B series airplanes with bottom engine vibration isolators affected by material degradation as identified through maintenance records review.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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