# N51AG: 1971 Bell UH-1H - Status: Valid registration - Airframe: [Bell UH-1H](https://openairdocs.org/model/bell-uh-1h) (registry code 1181407, 15 seats) - Engine: [Amateur-built UNKNOWN ENG](https://openairdocs.org/engine/amateur-built-unknown-eng) (registry code 99999) - Serial number: 71-20178 - Year built: 1971 - Type: Rotorcraft - Engine type: Turbo-shaft - Airworthiness: Restricted, agriculture and pest control, forest, other - Airworthiness date: July 17, 1997 - Certificate issued: December 11, 2014 - Expires: December 31, 2027 - Mode S code: A65F1D - Registered owner: [Brown Helicopter Inc](https://openairdocs.org/faa-owner/BROWN%20HELICOPTER%20INC) - Location: [Pensacola, FL](https://openairdocs.org/faa-place/FL/Pensacola) - Owner type: Corporation - Owner's area on the map: 30.3919° N, 87.3720° W: Placed by OpenAirDocs at the center of ZIP code 32506, within about 3 miles (OpenAirDocs). The owner's mailing address, not where the aircraft is based - FAA registry: https://registry.faa.gov/AircraftInquiry/Search/NNumberResult?nNumberTxt=51AG - Page: https://openairdocs.org/aircraft/N51AG From the FAA registry file of October 24, 2026. ADs below are matched by the registry's airframe and engine model codes. They may apply; each AD's applicability can narrow it by serial number, part number or installed equipment. This is not a compliance determination. ## ADs that may apply (OpenAirDocs): 26 in force ### Matched by airframe (Bell UH-1H) - [AD 2024-19-17](https://openairdocs.org/ad/2024-19-17): Rotorcraft flight control · Airwolf Aerospace, LLC Tension-Torsion Strap Assemblies, P/N… (STC SR03408CH). Effective Oct 11, 2024 - [AD 2022-20-14](https://openairdocs.org/ad/2022-20-14): Main Rotor Gearbox · Bell Textron 204B, 205A, 205A-1 and 20 more. Effective Dec 27, 2022 - [AD 2022-22-12](https://openairdocs.org/ad/2022-22-12): Nose/Tail Landing Gear Structure/Axle · Replacement crosstubes P/N D212-664 (Dart Aerospace STC SR01298NY). Effective Nov 22, 2022 - [AD 2022-21-11](https://openairdocs.org/ad/2022-21-11): Main rotor blades · Bell Textron 204B, 205A, 205A-1 and 11 more. Effective Nov 16, 2022 - [AD 2022-05-10](https://openairdocs.org/ad/2022-05-10): Cabin Equipment/Furnishings · Airbus Helicopters AS332L, AS332L1, AS332L2 and 57 more. Effective Apr 20, 2022 - [AD 2022-06-05](https://openairdocs.org/ad/2022-06-05): Main Rotor System · WSH HH-1K, TH-1F, TH-1L and 11 more. Effective Mar 16, 2022 - [AD 2021-15-14](https://openairdocs.org/ad/2021-15-14): Rotorcraft Tail Boom · California Department of Forestry UH-1H, UH-1F, TH-1L and 39 more. Effective Aug 30, 2021 - [AD 2014-03-10](https://openairdocs.org/ad/2014-03-10): Tail Rotor Control System · JJASPP Engineering Services UH-1H, UH-1F, TH-1L and 35 more. Effective Mar 26, 2014 - [AD 2013-13-06](https://openairdocs.org/ad/2013-13-06): Main rotor head · California Department of Forestry UH-1H, UH-1F, TH-1L and 36 more. Effective Sep 10, 2013 - [AD 2013-13-14](https://openairdocs.org/ad/2013-13-14): Main Rotor Head · JJASPP Engineering Services UH-1H, UH-1F, TH-1L and 33 more. Effective Jul 24, 2013 - [AD 2012-17-10](https://openairdocs.org/ad/2012-17-10): Main Rotor Blades · California Department of Forestry UH-1H, UH-1F, TH-1L and 36 more. Effective Sep 28, 2012 - [AD 2012-14-12](https://openairdocs.org/ad/2012-14-12): Tail Rotor Blades · California Department of Forestry UH-1H, UH-1F, TH-1L and 36 more. Effective Sep 4, 2012 - [AD 2006-19-05](https://openairdocs.org/ad/2006-19-05): Tail rotor (T/R) slider · California Department of Forestry UH-1H, UH-1F, TH-1L and 36 more. Effective Oct 16, 2006 - [AD 2002-20-01](https://openairdocs.org/ad/2002-20-01): TT strap · Overseas Aircraft Support UH-1H, UH-1F, TH-1L and 34 more. Effective Nov 6, 2002 - [AD 2002-13-51](https://openairdocs.org/ad/2002-13-51): Tail Rotor (T/R) Grip · Overseas Aircraft Support UH-1H, UH-1F, TH-1L and 34 more. Effective Aug 19, 2002 - [AD 2002-01-31](https://openairdocs.org/ad/2002-01-31): Retirement Index Number (RIN) for Masts · Overseas Aircraft Support UH-1H, UH-1F, TH-1L and 36 more. Effective Mar 8, 2002 - [AD 2000-15-21 R1](https://openairdocs.org/ad/2000-15-21-R1): Main Rotor Mast Assemblies · Overseas Aircraft Support UH-1H, UH-1F, TH-1L and 33 more. Effective Nov 22, 2000 - [AD 99-25-12](https://openairdocs.org/ad/99-25-12): Tailboom Vertical Fin Spar · California Department of Forestry UH-1H, UH-1F, TH-1L and 31 more. Effective Jan 11, 2000 - [AD 99-07-15](https://openairdocs.org/ad/99-07-15): Tail Rotor Yoke · Arrow Falcon Exporters UH-1H, UH-1F, TH-1L and 33 more. Effective May 3, 1999 - [AD 97-01-06](https://openairdocs.org/ad/97-01-06): Tail Rotor Slider · Arrow Falcon Exporters UH-1H, UH-1F, TH-1L and 32 more. Effective Feb 13, 1997 - [AD 96-12-26](https://openairdocs.org/ad/96-12-26): Clean and Inspect Tail Rotor Blade · Arrow Falcon Exporters UH-1H, UH-1F, TH-1L and 36 more. Effective Sep 23, 1996 - [AD 95-10-08](https://openairdocs.org/ad/95-10-08): Tail Rotor Control System · Arrow Falcon Exporters UH-1H, UH-1F, TH-1L and 34 more. Effective May 26, 1995 - [AD 94-22-09](https://openairdocs.org/ad/94-22-09): Tail Rotor Driveshaft · Arrow Falcon Exporters UH-1H, UH-1F, TH-1L and 34 more. Effective Nov 22, 1994 - [AD 92-23-01](https://openairdocs.org/ad/92-23-01): Main Rotor Pillow Blocks · Bell Helicopter Textron 204B, 205A, 205A-1 and 10 more. Effective Apr 23, 1993 - [AD 90-03-10](https://openairdocs.org/ad/90-03-10): Tail Rotor Grips · Arrow Falcon Exporters UH-1H, UH-1F, 204B and 33 more. Effective Oct 18, 1991 - [AD 90-10-05](https://openairdocs.org/ad/90-10-05): Tail Rotor Gearbox · Bell Helicopter Textron TH-1L, UH-1E, UH-1L and 17 more. Effective Jun 5, 1990 ### Matched by engine (Amateur-built UNKNOWN ENG) None in force. ### Historical (superseded or no longer in force) - [AD 2021-15-52](https://openairdocs.org/ad/2021-15-52) (historical): Main Rotor System · Arrow Falcon Exporters UH-1H, UH-1F, TH-1L and 39 more. Effective Aug 13, 2021 - [AD 80-17-09](https://openairdocs.org/ad/80-17-09) (historical): Main Rotor Straps · Bell Helicopter Textron 204B, 205A-1, 212 and 16 more. Effective Sep 15, 1980 ## Information bulletins (advisory) (2 in force) - [SAIB SW-18-29R1](https://openairdocs.org/saib/SW-18-29R1): Rotorcraft Tail Boom, Attach Structure Failure. Issued Feb 19, 2019 - [SAIB SW-12-38](https://openairdocs.org/saib/SW-12-38): Emergency Push Out Window Retention. Issued Jul 30, 2012 - [SAIB SW-18-29](https://openairdocs.org/saib/SW-18-29) (historical): Rotorcraft Tail Boom, Attach Structure Failure. Issued Oct 1, 2018 ## NTSB investigations (1) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB ATL05LA035](https://openairdocs.org/ntsb/ATL05LA035), Dec 16, 2004: Bell UH-1H (N51AG), Rockford, AL, substantial damage. Probable cause: The pilot's failure to maintain adequate obstacle clearance, which resulted in an in-flight collision with a tree. ## NTSB investigations on N51AG not matched to an aircraft (1) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB FTW83LA173](https://openairdocs.org/ntsb/FTW83LA173), Mar 31, 1983: Anderson, Greenwood 51 (N51AG), Tomball, TX, substantial damage ## FAA accident and incident reports (2) From the FAA Accident/Incident Data System. Reports are matched to registry aircraft by N-number and event date, checked against the reported make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [Accident 20041215033109A](https://openairdocs.org/incident/20041215033109A), Dec 15, 2004: Bell UH1H (N51AG), Rockford, AL, Substantial damage. (-23) While performing aerial applications over timber land, pilot reported a loud "bang" and loss of tail rotor effectiveness at the apex of the spray turn.… - [Incident 19960717023739I](https://openairdocs.org/incident/19960717023739I), Jul 17, 1996: Bell UH1H (N51AG), Selingsgrove, PA. Narrative: on July 17, 1996 at 1730 hours local time, a Bell model UH-1H helicopter, N51AG, registered to agrotors, inc., made a precautionary landing in a… ## Reports on N51AG not matched to an aircraft (2) They name N51AG, but no registry record covers the date, the aircraft registered then was built later, or the report describes another aircraft. - [Accident 19830331010499A](https://openairdocs.org/incident/19830331010499A), Mar 31, 1983: Blanca 51ARIES (N51AG), Tomball, TX, Substantial damage. Tried to make sharp turn on taxiway but brake failed. Ran off into soft ground. Main gear hit a hole and collapsed. - [Incident 19820111002029I](https://openairdocs.org/incident/19820111002029I), Jan 11, 1982: Blanca 51ARIES (N51AG), Houston, TX, Minor damage. Zg zt fumes in cockpit and engine vibration. Propeller spinner bulkhead failed at propeller attach bolt area. ## Service difficulty reports (22) As reported by operators and repair stations. Matched to this aircraft by N-number and event date, checked against the reported serial number, make and model. - [SDR LS12003F00000](https://openairdocs.org/sdr/LS12003F00000), Jun 6, 2003: SKIN. CRACKED. THE TAILBOOM FIRST 2 UPPER SKINS HAD NUMEROUS CRACKS. UNDER NORMAL OPERATIONS THESE CRACKS WOULD NEVER MATERIALIZE. THE AIRCRAFT HAS BEEN DOING LIFTING WORK. MU - [SDR LS1R074916](https://openairdocs.org/sdr/LS1R074916), Jul 20, 2001: BATTERY. WEAK. PART IS WEAK. - [SDR LS1R072190](https://openairdocs.org/sdr/LS1R072190), Apr 10, 2001: CABLE DRUM. STRETCHED. CABLE DRUM STRETCHED. - [SDR LS1R066445](https://openairdocs.org/sdr/LS1R066445), Feb 29, 2000: BEARING. ROUGH. BEARING EXTREMELY ROUGH, AND RATCHETY. - [SDR 99ZZZX3932](https://openairdocs.org/sdr/99ZZZX3932), Sep 8, 1999: SWITCH. MALFUNCTIONED. TRANSMISSION OIL HOT LIGHT COMES ON INTERMITTENTLY WITH TEMPERATURE IN GREEN. REMOVED AND REPLACED. - [SDR 99ZZZX3891](https://openairdocs.org/sdr/99ZZZX3891), Sep 8, 1999: INDICATOR. MALFUNCTIONED. INDICATING FALSE AIRSPEED, SLOW TO CHANGE INDICATION. REMOVED AND REPLACED. - [SDR 99ZZZX3889](https://openairdocs.org/sdr/99ZZZX3889), Sep 8, 1999: INDICATOR. MALFUNCTIONED. INDICATING FALSE AIRSPEED. SLOW TO CHANGE INDICATION. REMOVED AND REPLACED. - [SDR 99ZZZX3890](https://openairdocs.org/sdr/99ZZZX3890), Sep 7, 1999: PUMP. MALFUNCTIONED. HEARD NOISE FROM LEFT FUEL CELL. CHECKED PRESSURE ON BOOST PUMP, FOUND TO BE LOW. REMOVED AND REPLACED PUMP. - [SDR 99ZZZX2764](https://openairdocs.org/sdr/99ZZZX2764), Jul 9, 1999: CAUTION PANEL. MALFUNCTIONED. TRANSMISSION OIL HOT LIGHT CAME ON, TEMPERATURE GAUGE IS NORMAL. REMOVED AND REPLACED. - [SDR 99ZZZX2497](https://openairdocs.org/sdr/99ZZZX2497), Jun 10, 1999: TRANSCEIVER. FAILED. TRANSCEIVER WOULD NOT TRANSMIT. REMOVED AND REPLACED. - [SDR 99ZZZX2493](https://openairdocs.org/sdr/99ZZZX2493), Jun 10, 1999: SKID TUBE. DENTED. SKID TUBE DENTED. REMOVED AND REPLACED. - [SDR 99ZZZX2492](https://openairdocs.org/sdr/99ZZZX2492), Jun 10, 1999: SKID TUBE. DENTED. SKID TUBE DENTED. REMOVED AND REPLACED. - [SDR 99ZZZX2245](https://openairdocs.org/sdr/99ZZZX2245), May 12, 1999: ALTIMETER. MALFUNCTIONED. ALTIMETER HAD EXCESSIVE FRICTION. FAILED CERTIFICATION. REMOVED AND REPLACED. - [SDR 99ZZZX2244](https://openairdocs.org/sdr/99ZZZX2244), Apr 29, 1999: AUDIO PANEL. MALFUNCTIONED. AUDIO PANEL CAUSES STATIC IN PILOT'S HEAD SET. - [SDR 98ZZZX3860](https://openairdocs.org/sdr/98ZZZX3860), Sep 23, 1998: TRANSPONDER. FAILED. TRANSPONDER WOULD NOT TEST. SENT FOR REPAIR. - [SDR 98ZZZX3633](https://openairdocs.org/sdr/98ZZZX3633), Sep 14, 1998: ENCODER. FAILED. ENCODER TRIPS CIRCUIT BREAKER. REMOVED AND REPLACED. - [SDR 98ZZZX3637](https://openairdocs.org/sdr/98ZZZX3637), Sep 10, 1998: REGULATOR. FAILED. WILL NOT REGULATE VOLTAGE. REPLACED. - [SDR 98ZZZX3548](https://openairdocs.org/sdr/98ZZZX3548), Jul 10, 1998: DRIVESHAFT. DAMAGED. BALANCED WEIGHT NOT INSTALLED. DRIVESHAFT WAS REPLACED. - [SDR 98ZZZX2789](https://openairdocs.org/sdr/98ZZZX2789), Jul 1, 1998: INDICATOR. FAILED. ATTITUDE INDICATOR WILL NOT CAGE. REMOVED FROM AIRCRAFT. - [SDR 98ZZZX2100](https://openairdocs.org/sdr/98ZZZX2100), May 13, 1998: REGULATOR. FAILED. VOLTAGE REGULATOR WILL NOT HOLD A VOTLAGE SETTING, KEEPS FLUCTUATING. SENT FOR REPAIR. REF: CONTROL NR 98-5-8. - [SDR 98ZZZX1738](https://openairdocs.org/sdr/98ZZZX1738), Apr 24, 1998: REGULATOR. FAILED. VOLTAGE REGULATOR WILL NOT STAY ON LINE AND CANNOT BE ADJUSTED. REMOVED AND REPLACED AND SENT FOR REPAIR. CONTROL NR 98-4-11. - [SDR 96ZZZX3912](https://openairdocs.org/sdr/96ZZZX3912), Jul 25, 1996: HOSE. CHAFED. DURING STRAIGHT AND LEVEL FLIGHT, PILOT NOTICED FLIGHT CONTROLS STARTING TO FEEL STIFF. THIS WAS IMMEDIATELY FOLLOWED BY A DROP IN HYDRAULIC PRESSURE. PILOT LAN ## STCs that may be installed (OpenAirDocs) None matched to this aircraft's models. ## Related - Other Bell UH-1H aircraft: https://openairdocs.org/model/bell-uh-1h/aircraft.md - The Amateur-built UNKNOWN ENG engine: https://openairdocs.org/engine/amateur-built-unknown-eng.md --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.