AD 97-14-04
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | The Boeing Company | 737-100 Series | Airworthiness Directives; Boeing Model 737-100, -200, -300, -400, and -500 Series Airplanes |
| aircraft | The Boeing Company | 737-200 Series | Airworthiness Directives; Boeing Model 737-100, -200, -300, -400, and -500 Series Airplanes |
| aircraft | The Boeing Company | 737-300 Series | Airworthiness Directives; Boeing Model 737-100, -200, -300, -400, and -500 Series Airplanes |
| aircraft | The Boeing Company | 737-400 Series | Airworthiness Directives; Boeing Model 737-100, -200, -300, -400, and -500 Series Airplanes |
| aircraft | The Boeing Company | 737-500 Series | Airworthiness Directives; Boeing Model 737-100, -200, -300, -400, and -500 Series Airplanes |
Unsafe Condition
Fracturing of the vernier control rod bolts due to the shank of the bolt running into the threads on the nutplate during installation, which could result in uncommanded movements of the rudder and consequent reduced controllability of the airplane.
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Required Actions
Replace the main rudder power control unit (PCU) with newly designed units having specific part numbers, replace vernier control rod bolts with newly designed bolts, perform leak tests of the PCU at specified intervals, and revise the FAA-approved maintenance program to include the leak test requirements.
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Compliance Time
Within 2 years after the effective date of this AD (August 4, 1997) for replacement actions, and leak tests must be performed within 4,000 flight hours after the effective date (for applicable airplanes) or within 6,400 flight hours after PCU replacement, with subsequent intervals not exceeding 6,400 flight hours.
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Affected Aircraft
Boeing Model 737-100, -200, -300, -400, and -500 Series airplanes.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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