AD 97-23-06
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Schweizer Aircraft Corporation | 269A | Airworthiness Directives; Schweizer Aircraft Corporation Model 269A, A-1, B, and C, and TH-55A Helicopters |
| aircraft | Schweizer Aircraft Corporation | 269A-1 | Airworthiness Directives; Schweizer Aircraft Corporation Model 269A, A-1, B, and C, and TH-55A Helicopters |
| aircraft | Schweizer Aircraft Corporation | 269B | Airworthiness Directives; Schweizer Aircraft Corporation Model 269A, A-1, B, and C, and TH-55A Helicopters |
| aircraft | Schweizer Aircraft Corporation | 269C | Airworthiness Directives; Schweizer Aircraft Corporation Model 269A, A-1, B, and C, and TH-55A Helicopters |
Unsafe Condition
Failure of the ring gear, loss of drive to the main rotor gearbox, and a subsequent forced landing.
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Required Actions
Inspect the ring gear teeth for surface deterioration (pitting, excessive wearing, cracking, or corrosion) per Schweizer Service Bulletin B-244.2. Replace the ring gear with P/N 269A5104-7 (S/N S2100 or higher) if deterioration is found or during main rotor transmission overhaul.
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Compliance Time
Before further flight if specific issues are detected; within 50 hours time-in-service (TIS) after the effective date or next annual inspection, whichever comes first. Thereafter, inspections every 50 hours TIS.
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Affected Aircraft
Schweizer Model 269A, A-1, B, C, and TH-55A helicopters with main rotor transmission ring gear (P/N 269A5104-5) marked EGC, ACR, or manufacturer codes 23751/57152.
AI-generated summary from the source AD text. Verify against the official source before acting.
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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