AD 75-01-06
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Airesearch | The Boeing Company | Auxiliary Power Units | Airworthiness Directives; AIRESEARCH MANUFACTURING COMPANY of ARIZONA: Applies to model GTCP660-4 (prior to Serial No. P37808) and GTCP660-4R (Prior to Serial No. P133) Auxiliary Power Units |
| aircraft | Airesearch | The Boeing Company | 747-100 Series | Airworthiness Directives; AIRESEARCH MANUFACTURING COMPANY of ARIZONA: Applies to model GTCP660-4 (prior to Serial No. P37808) and GTCP660-4R (Prior to Serial No. P133) Auxiliary Power Units |
| aircraft | Airesearch | The Boeing Company | 747-100B Series | Airworthiness Directives; AIRESEARCH MANUFACTURING COMPANY of ARIZONA: Applies to model GTCP660-4 (prior to Serial No. P37808) and GTCP660-4R (Prior to Serial No. P133) Auxiliary Power Units |
| aircraft | Airesearch | The Boeing Company | 747-100B SUD Series | Airworthiness Directives; AIRESEARCH MANUFACTURING COMPANY of ARIZONA: Applies to model GTCP660-4 (prior to Serial No. P37808) and GTCP660-4R (Prior to Serial No. P133) Auxiliary Power Units |
| aircraft | Airesearch | The Boeing Company | 747-200B Series | Airworthiness Directives; AIRESEARCH MANUFACTURING COMPANY of ARIZONA: Applies to model GTCP660-4 (prior to Serial No. P37808) and GTCP660-4R (Prior to Serial No. P133) Auxiliary Power Units |
| aircraft | Airesearch | The Boeing Company | 747-200C Series | Airworthiness Directives; AIRESEARCH MANUFACTURING COMPANY of ARIZONA: Applies to model GTCP660-4 (prior to Serial No. P37808) and GTCP660-4R (Prior to Serial No. P133) Auxiliary Power Units |
| aircraft | Airesearch | The Boeing Company | 747-200F Series | Airworthiness Directives; AIRESEARCH MANUFACTURING COMPANY of ARIZONA: Applies to model GTCP660-4 (prior to Serial No. P37808) and GTCP660-4R (Prior to Serial No. P133) Auxiliary Power Units |
| aircraft | Airesearch | The Boeing Company | 747-300 Series | Airworthiness Directives; AIRESEARCH MANUFACTURING COMPANY of ARIZONA: Applies to model GTCP660-4 (prior to Serial No. P37808) and GTCP660-4R (Prior to Serial No. P133) Auxiliary Power Units |
| aircraft | Airesearch | The Boeing Company | 747-400 Series | Airworthiness Directives; AIRESEARCH MANUFACTURING COMPANY of ARIZONA: Applies to model GTCP660-4 (prior to Serial No. P37808) and GTCP660-4R (Prior to Serial No. P133) Auxiliary Power Units |
| aircraft | Airesearch | The Boeing Company | 747-400D Series | Airworthiness Directives; AIRESEARCH MANUFACTURING COMPANY of ARIZONA: Applies to model GTCP660-4 (prior to Serial No. P37808) and GTCP660-4R (Prior to Serial No. P133) Auxiliary Power Units |
Unsafe Condition
Fatigue cracks in the fuel pump body, part numbers 968502-2 and -3, could lead to fuel system failure.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Install a placard prohibiting inflight or taxi APU operation depending on cycles. Inspect fuel pump body for cracks and check relief valve setting per service bulletin. Replace cracked units with inspected or new parts. Recurring inspections at 2,500 cycle intervals after initial checks.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Within 15 days time in service after the effective date of this AD, and within 500 APU operating cycles after the effective date.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
AIRESEARCH MANUFACTURING COMPANY of ARIZONA model GTCP660-4 (prior to Serial No. P37808) and GTCP660-4R (Prior to Serial No. P133) Auxiliary Power Units installed in Boeing B-747 series airplanes.
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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