# N9739C: 1956 Hiller UH-12C

- Status: Valid registration
- Airframe: [Hiller UH-12C](https://openairdocs.org/model/hiller-uh-12c) (registry code 4360116, 4 seats)
- Engine: [Franklin 6V4 series](https://openairdocs.org/engine/franklin-6v4-series) (registry code 27033)
- Data sheets: [TCDS 6H2](https://openairdocs.org/tcds/6H2) (Siam Hiller Holdings Inc.), [TCDS E-244](https://openairdocs.org/tcds/E-244) (Franklin Sp. z.o.o.) (OpenAirDocs)
- Serial number: 847
- Year built: 1956
- Type: Rotorcraft
- Engine type: Reciprocating
- Airworthiness: Standard
- Airworthiness date: November 21, 1962
- Certificate issued: April 3, 2012
- Expires: April 30, 2028
- Mode S code: AD9260
- Registered owner: [Mullins Michael](https://openairdocs.org/faa-owner/MULLINS%20MICHAEL)
- Location: [Seaford, DE](https://openairdocs.org/faa-place/DE/Seaford)
- Owner type: Individual
- Owner's area on the map: 38.6345° N, 75.6236° W: Placed by OpenAirDocs at the center of ZIP code 19973, within about 5 miles (OpenAirDocs). The owner's mailing address, not where the aircraft is based
- FAA registry: https://registry.faa.gov/AircraftInquiry/Search/NNumberResult?nNumberTxt=9739C
- Page: https://openairdocs.org/aircraft/N9739C

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. The registry lists only the engine series, so ADs for every Franklin 6V4 model are included.

## ADs that may apply (OpenAirDocs): 19 in force

### Matched by airframe (Hiller UH-12C)

- [AD 2023-11-07](https://openairdocs.org/ad/2023-11-07): Ground Proximity System · Airbus Helicopters 47, 206, 210 and 237 more. Effective Jun 22, 2023
- [AD 2015-20-51](https://openairdocs.org/ad/2015-20-51): Hiller UH-12, UH-12A, UH-12B and 6 more
- [AD 2000-24-21](https://openairdocs.org/ad/2000-24-21): Control System Linkage · Hiller UH-12, UH-12A, UH-12B and 6 more. Effective Jan 10, 2001
- [AD 97-20-15](https://openairdocs.org/ad/97-20-15): Outboard Tension-Torsion Bar Pin · Hiller UH-12A, UH-12B, UH-12C and 2 more. Effective Nov 12, 1997
- [AD 97-10-16](https://openairdocs.org/ad/97-10-16): Blade Spar Tube and Cuff Inspection · Allison 250-C20/250-C20B engine (Siam Hiller Holdings STC SH177WE or SH178WE). Effective Jun 27, 1997
- [AD 83-25-02](https://openairdocs.org/ad/83-25-02): Main Rotor Blade Doublers · Allison 250-C20/250-C20B engine (Siam Hiller Holdings STC SH177WE). Effective Dec 29, 1983
- [AD 81-18-02](https://openairdocs.org/ad/81-18-02): Tail Rotor Skin Cracks · Hiller UH-12, UH-12A, UH-12B and 6 more. Effective Sep 10, 1981
- [AD 81-17-03](https://openairdocs.org/ad/81-17-03): Main Transmission · Hiller UH-12, UH-12A, UH-12B and 6 more. Effective Aug 24, 1981
- [AD 81-17-01](https://openairdocs.org/ad/81-17-01): Starting Vibrator Assemblies · Bendix Starting Vibrator Assemblies, B-2, B-2A and 49 more. Effective Aug 13, 1981
- [AD 77-24-03](https://openairdocs.org/ad/77-24-03): Fuel Control Valve · Hiller UH-12C, UH-12D, UH-12L and 3 more. Effective Jan 6, 1978
- [AD 73-20-03](https://openairdocs.org/ad/73-20-03): Main Rotor Hub · Hiller UH-12, UH-12A, UH-12B and 4 more. Effective Oct 30, 1973
- [AD 71-25-08](https://openairdocs.org/ad/71-25-08): Inspect Main Rotor Blades · Hiller UH-12, UH-12A, UH-12B and 6 more. Effective Dec 14, 1971
- [AD 63-04-02](https://openairdocs.org/ad/63-04-02): Tail Rotor Blade · Hiller UH-12, UH-12A, UH-12B and 1 more. Effective Feb 12, 1963
- [AD 59-25-03](https://openairdocs.org/ad/59-25-03): Wobble Plate Screws · Hiller UH-12, UH-12A, UH-12B and 3 more
- [AD 59-05-05](https://openairdocs.org/ad/59-05-05): Cyclic Control Scissor Casting · Hiller UH-12, UH-12A, UH-12B and 3 more
- [AD 58-02-03](https://openairdocs.org/ad/58-02-03): Carburetor Mixture Control Removal · Hiller UH-12, UH-12A, UH-12B and 2 more
- [AD 56-09-01](https://openairdocs.org/ad/56-09-01): Tail Rotor Torsion Bar · Hiller UH-12, UH-12A, UH-12B and 1 more

### Matched by engine (Franklin 6V4 series)

- [AD 69-09-01](https://openairdocs.org/ad/69-09-01): Eisemann Magnetos · Eisemann Magnetos, 2A4-45-B2, 2A4-49-B2 and 158 more
- [AD 51-28-02](https://openairdocs.org/ad/51-28-02): Oil Pump Gears · Wytwornia Sprzetu Komunikacyjnego 6V4-178-B3, 6V4-178-B31, 6V4-178-B32 and 3 more

### Historical (superseded or no longer in force)

- [AD 2021-23-13](https://openairdocs.org/ad/2021-23-13) (historical): Ground Proximity System · Airbus Helicopters K-225, K-190A, K-240 and 237 more. Effective Dec 9, 2021
- [AD 77-07-05 R1](https://openairdocs.org/ad/77-07-05-R1) (historical): Control Rotor Blade Spar Tube and Cuff · Hiller UH-12, UH-12A, UH-12B and 3 more. Effective Jun 20, 1977
- [AD 77-07-05](https://openairdocs.org/ad/77-07-05) (historical): Control Rotor Blade Spar Tube and Cuff · Hiller UH-12, UH-12A, UH-12B and 3 more. Effective Jun 20, 1977

## Information bulletins (advisory)

None matched.

## 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 CHI99LA012](https://openairdocs.org/ntsb/CHI99LA012), Oct 24, 1998: Hiller UH-12C (N9739C), Clinton, IA, substantial damage. Probable cause: the failure of the 90 degree gearbox for reasons undetermined. Factors were the failure of the gearbox, and it not being possible for the pilot to maintain control of the aircraft.

## 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 19981024040399A](https://openairdocs.org/incident/19981024040399A), Oct 24, 1998: Hiller UH12C (N9739C), Clinton, IA, Substantial damage. (-23) While in cruise flight, the pilot was unable to maintain altitude and heading. An emergency landing was initiated which resulted in loss of control…
- [Incident 19781020029159I](https://openairdocs.org/incident/19781020029159I), Oct 20, 1978: Hiller UH12C (N9739C), Carbondale, IL, Minor damage. Student delayed in leveling after a practice autorotation. Tail rotor struck the ground.

## Service difficulty reports

None filed for this aircraft. Matched to this aircraft by N-number and event date, checked against the reported serial number, make and model.

## STCs that may be installed (OpenAirDocs) (37)

Approved for this aircraft's airframe or engine model, in force first, then newest. The registry doesn't record which STCs an aircraft has; its records do.

### Approved for the airframe (Hiller UH-12C)

- [STC SH3319NM](https://openairdocs.org/stc/SH3319NM): Installation of Precise Flight Pulselite Control Unit in the Landing /Taxi Recognition Visual Control Light system,. Precise Flight Inc
- [STC SR02704SE](https://openairdocs.org/stc/SR02704SE): Installation and maintenance of the Sunspot 36 and 46 series lights. AeroLED's Holdings LLC
- [STC SR00359BO](https://openairdocs.org/stc/SR00359BO): Installation of Parmetheus Plus LED PAR36 and PAR46 taxi and landing lights. Whelen Aerospace Technologies
- [STC SR00420NY](https://openairdocs.org/stc/SR00420NY): Installation of Airwolf remote mounted engine oil filter Model AFC-600. Airwolf Filter, Corp
- [STC SR02394AK](https://openairdocs.org/stc/SR02394AK): Replacement of existing landing and/or hover light bulbs with Light Emitting Diode (LED) lighting system. Seaplanes North LLC
- [STC SA00068SE](https://openairdocs.org/stc/SA00068SE): Installation of fuel flow/pressure instruments. (W/TSIO-360-MB1). Electronics International Inc
- [STC SA2693NM](https://openairdocs.org/stc/SA2693NM): Installation of Electronics International digital volt/amp gauges and accessories. Electronics International Inc
- [STC SA02033AT](https://openairdocs.org/stc/SA02033AT): Modification to install an air-oil separator to prevent oil from being aspirated from the engine breather line. M-20 Oil Separators LLC
- [STC SA00680SE](https://openairdocs.org/stc/SA00680SE): Installation of Electronics International model UBG-16 or UBG-16T bar graph engine analyzer. Electronics International
- [STC SA02520AT](https://openairdocs.org/stc/SA02520AT): Installation of M-20 Oil Separator, model 600-WP. M-20 Oil Separators LLC
- [STC SA2687NM](https://openairdocs.org/stc/SA2687NM): Installation of Truboplus/ Electronics Int'l gauges and switches. Aero Manufacturing Inc
- [STC SA1626NM PAGE 1](https://openairdocs.org/stc/SA1626NM%20PAGE%201): Installation of Electronics Int'l Digital EGT/CHT Instruments and accessories. (201 Series). Electronics International
- [STC SA2350NM PAGE 1](https://openairdocs.org/stc/SA2350NM%20PAGE%201): Installation of Electronics International Inc digital carburetor/outside air temperature gauges. Electronics International
- [STC SA4302NM](https://openairdocs.org/stc/SA4302NM): Installation of Electronics Int'l digital automatic engine analyzer. Electronics International
- [STC SA3862NM PAGE 1](https://openairdocs.org/stc/SA3862NM%20PAGE%201): Installation of Electronics International Primary TIT/EGT/CHT instruments, remote switches and associated accessories. Electronics International
- [STC SA2190NM PAGE 1](https://openairdocs.org/stc/SA2190NM%20PAGE%201): Installation of electronics International Digital Volt/Amp Gauges and Accessories. Electronics International
- [STC SA1351WE](https://openairdocs.org/stc/SA1351WE): Replace existing fabric on wings, fuselage, empennage, and/or control surfaces, with Ceconite101 material. (262A Series -12). Ceconite Inc
- [STC SH959NW](https://openairdocs.org/stc/SH959NW): Remobe battery from Sta 126 and install it on the original radio rack at Sta 25. Clover Park Vocational/Technical Institute
- [STC SH954NW](https://openairdocs.org/stc/SH954NW): Remove battery from Sta 126 and install it on the original radio ract at Sta 25. Clover Park Vocational/Technical Institute
- [STC SH141GL](https://openairdocs.org/stc/SH141GL): Installation of Bell 47 canopy and one piece doors. Stanley Tool & Die Co
- [STC SH446EA](https://openairdocs.org/stc/SH446EA): Installation of Franklin engine Model 6V-350B in Fairchild Hiller UH-12A helicopter. Franklin Engine Co Inc. Lists UH-12 Series
- [STC SH82WE](https://openairdocs.org/stc/SH82WE): Installation of spray system and extended landing gear. Wayne Clevenger
- [STC SH83WE](https://openairdocs.org/stc/SH83WE): Installation of modified air induction system. Wayne Clevenger
- [STC SH80WE](https://openairdocs.org/stc/SH80WE): Installation of Simplex thirty-two foot spray boom. Simplex Manufacturing Co. Lists UH-12 Series
- [STC SH1-457](https://openairdocs.org/stc/SH1-457): Aircooler Motors 6VS-335B turbo-supercharged engine (derated). Carson Helicopters Inc. Lists UH-12 Series
- [STC SH160AL](https://openairdocs.org/stc/SH160AL): Airborne control survey system. US Dept of Interior. Lists UH-12 Series
- [STC SH4-178](https://openairdocs.org/stc/SH4-178): Curved control stick. Nystrom Aviation Inc. Lists UH-12 Series
- [STC SH52WE](https://openairdocs.org/stc/SH52WE): High volume fifty foot spray boom kit. Simplex Manufacturing Co. Lists UH-12 Series
- [STC SH77AL](https://openairdocs.org/stc/SH77AL): Tundra snow shoes. ERA Helicopters Inc. Lists UH-12 Series
- [STC SH9AL](https://openairdocs.org/stc/SH9AL): Airglas tundra pads L-100. Intl Helicopters. Lists UH-12 Series
- [STC SA2350NM](https://openairdocs.org/stc/SA2350NM) (historical): Installation of Electronics International Inc digital carburetor/outside air temperature gauges listed on the attached continuation sheet and the associated accessories. Electronics International

### Approved for the engine (Franklin 6V4 series)

- [STC SE04651CH](https://openairdocs.org/stc/SE04651CH): To allow use of l00R grade aviation fuel meeting Swift Fuel, LLC specification SPEC-l00R-22. Swift Fuels LLC. Lists 6V4-200-C32
- [STC SE2932SW](https://openairdocs.org/stc/SE2932SW): Install carburetor air temperature indicator. Approved for Aircooled Motors (Franklin Engine Co.) equipped with float carburetors. Model eligibility included here may not be inclusive. Alcor LLC. Lists 6V4-178-B3
- [STC SE1311SO](https://openairdocs.org/stc/SE1311SO): Installation of Shivers carburetor temperature gauge with a Richter Aero Equipment B-5 carburetor temperature probe. LegacySTC.com. Lists 6V4-178-B3
- [STC SE03309CH](https://openairdocs.org/stc/SE03309CH): Installation of Engine Preheat Kit, p/n TSP6CYL-2927-115 for 115 volt application. Hartzell Propeller Inc. Lists 6V4-178-B3
- [STC SE01966WI](https://openairdocs.org/stc/SE01966WI): Use of GAMI G100UL High Octane Unleaded Avgas in spark ignition piston aircraft engines. General Aviation Modifications Inc. Lists 6V4-178-B3
- [STC SE1-201](https://openairdocs.org/stc/SE1-201): Installation of the Richter Aero Equipment Type B-4 or B-5 Temperature Probe. (O-360 SERIES (excl. A1C, C2B, C2D)). MidContinent Instru Co Inc. Lists 6V4-178-B3

## Related

- Other Hiller UH-12C aircraft: https://openairdocs.org/model/hiller-uh-12c/aircraft.md
- The Franklin 6V4 series engine: https://openairdocs.org/engine/franklin-6v4-series.md

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