AD 60-26-05
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Lockheed Martin Corporation | 188A | LOCKHEED All Model 188 Series Aircraft |
| aircraft | Lockheed Martin Corporation | 188C | LOCKHEED All Model 188 Series Aircraft |
Unsafe Condition
Excessive free play in elevator counterweight linkage and potential rupture of elevator booster control valve viscous damper diaphragm could lead to elevator or control column oscillations, compromising flight control effectiveness.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Inspect elevator counterweight installation for free play exceeding 1/8-inch and reduce to 1/16-inch or less by replacing bolts/parts. Inspect viscous damper diaphragm for rupture and replace if found. Install spring-loaded cartridge (P/N 840404-1), replace damper with orifice type (P/N 492508-3), rework elevator booster assembly with orifice valve assembly (P/N 804551-1), and modify piston rod end with retaining washers (P/N 839756-1) per Service Bulletins 88/SB-498 and 524.
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Compliance Time
Within the next 1,000 hours' time in service.
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Affected Aircraft
Lockheed Model 188A and 188C aircraft, all serial numbers, as covered by AD 60-26-05.
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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