# N752A: 1957 Sikorsky S-55

- Status: Valid registration
- Airframe: [Sikorsky S-55](https://openairdocs.org/model/sikorsky-s-55) (registry code 8141602, 12 seats)
- Engine: [AiResearch TPE331 series](https://openairdocs.org/engine/airesearch-tpe331-series) (registry code 01517)
- Data sheets: [TCDS 1H4](https://openairdocs.org/tcds/1H4) (Centerpointe Aerospace Inc.) (OpenAirDocs)
- Serial number: 55981
- Year built: 1957
- Type: Rotorcraft
- Engine type: Turbo-shaft
- Airworthiness: Restricted, agriculture and pest control, weather control
- Airworthiness date: April 3, 1989
- Certificate issued: September 21, 2021
- Expires: September 30, 2028
- Mode S code: AA2177
- Registered owner: [Sierra Aeronautics LLC](https://openairdocs.org/faa-owner/SIERRA%20AERONAUTICS%20LLC)
- Location: [Franklin, KY](https://openairdocs.org/faa-place/KY/Franklin)
- Owner type: LLC
- Owner's area on the map: 36.7254° N, 86.5646° W: Placed by OpenAirDocs at the center of ZIP code 42134, within about 8 miles (OpenAirDocs). The owner's mailing address, not where the aircraft is based
- FAA registry: https://registry.faa.gov/AircraftInquiry/Search/NNumberResult?nNumberTxt=752A
- Page: https://openairdocs.org/aircraft/N752A

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 AiResearch TPE331 model are included.

## ADs that may apply (OpenAirDocs): 61 in force

### Matched by airframe (Sikorsky S-55)

- [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 66-04-03](https://openairdocs.org/ad/66-04-03): Main Rotor Blades · Orlando Helicopter Airways HRS-1/CH-19, HRS-3/H-19B, S-55 and 3 more. Effective Apr 27, 1976
- [AD 75-22-12](https://openairdocs.org/ad/75-22-12): Inflight Power Loss · Sikorsky S-55, S-55B and S-55C with STC SH125WE or SH127WE. Effective Oct 31, 1975
- [AD 75-04-02](https://openairdocs.org/ad/75-04-02): Main Rotor Spindles · Orlando Helicopter Airways CH-19E, H-19A, H-19D and 8 more. Effective Feb 19, 1975
- [AD 73-16-01](https://openairdocs.org/ad/73-16-01): Engine Turbine Failure · Sikorsky S-55, S-55B and S-55C with STC SH127WE. Effective Jul 31, 1973
- [AD 71-26-03](https://openairdocs.org/ad/71-26-03): Servo Support Bracket · Sikorsky S-55 and S62A. Effective Dec 30, 1971
- [AD 70-12-04](https://openairdocs.org/ad/70-12-04): Main Rotor Shaft Cracks · Sikorsky S-55, S-55B, S-55C and 1 more. Effective Jun 17, 1970
- [AD 67-29-07](https://openairdocs.org/ad/67-29-07): Azimuth Control Rod Assembly · Orlando Helicopter Airways HRS-1/CH-19, HRS-3/H-19B, S-55 and 2 more. Effective Nov 3, 1967
- [AD 67-17-06](https://openairdocs.org/ad/67-17-06): Pylon Lower Ring · Orlando Helicopter Airways HRS-1/CH-19, HRS-3/H-19B, S-55 and 2 more. Effective May 21, 1967
- [AD 65-08-02](https://openairdocs.org/ad/65-08-02): Main Rotor Blades · Orlando Helicopter Airways HRS-1/CH-19, HRS-3/H-19B, S-55 and 11 more. Effective Apr 9, 1965
- [AD 63-05-02](https://openairdocs.org/ad/63-05-02): Main Rotor Blades · Orlando Helicopter Airways HRS-1/CH-19, HRS-3/H-19B, S-55 and 2 more. Effective Mar 6, 1963
- [AD 60-13-04](https://openairdocs.org/ad/60-13-04): Rotor Shank Rod · Orlando Helicopter Airways HRS-1/CH-19, HRS-3/H-19B, S-51 and 3 more
- [AD 56-23-03](https://openairdocs.org/ad/56-23-03): Horizontal Hinge Pin Assembly · Orlando Helicopter Airways HRS-1/CH-19, HRS-3/H-19B, S-55 and 2 more
- [AD 56-16-03](https://openairdocs.org/ad/56-16-03): Main Rotor Blade Inspection · Orlando Helicopter Airways HRS-1/CH-19, HRS-3/H-19B, S-51 and 3 more
- [AD 55-25-04](https://openairdocs.org/ad/55-25-04): Tail Cone Skin Reinforcements · Orlando Helicopter Airways HRS-1/CH-19, HRS-3/H-19B, S-55 and 2 more
- [AD 54-20-02](https://openairdocs.org/ad/54-20-02): Support Assembly Cracks · Orlando Helicopter Airways HRS-1/CH-19, HRS-3/H-19B, S-55 and 2 more
- [AD 54-19-02](https://openairdocs.org/ad/54-19-02): Servo Safety Clip · Orlando Helicopter Airways HRS-1/CH-19, HRS-3/H-19B, S-55 and 2 more
- [AD 54-16-01](https://openairdocs.org/ad/54-16-01): Main Transmission · Orlando Helicopter Airways HRS-1/CH-19, HRS-3/H-19B, S-55 and 2 more
- [AD 54-13-01](https://openairdocs.org/ad/54-13-01): Star Assembly Bolt Replacement · Orlando Helicopter Airways HRS-1/CH-19, HRS-3/H-19B, S-55 and 2 more
- [AD 54-01-03](https://openairdocs.org/ad/54-01-03): Fuel Strainer Screen · Orlando Helicopter Airways HRS-1/CH-19, HRS-3/H-19B, S-55 and 2 more

### Matched by engine (AiResearch TPE331 series)

- [AD 2018-22-01](https://openairdocs.org/ad/2018-22-01): Turbine Section · Honeywell International TPE331-10, TPE331-10N, TPE331-10R and 8 more. Effective Dec 10, 2018
- [AD 2018-17-15](https://openairdocs.org/ad/2018-17-15): Turbine Engine Combustion Section · Honeywell International TPE331-1, TPE331-10, TPE331-10AV and 39 more. Effective Oct 22, 2018
- [AD 2018-13-05](https://openairdocs.org/ad/2018-13-05): Turbine Engine Reduction Gear · Honeywell International TPE331-1, TPE331-10, TPE331-10AV and 18 more. Effective Jul 26, 2018
- [AD 2016-21-07](https://openairdocs.org/ad/2016-21-07): Fuel control drive · Honeywell International TPE331-1, TPE331-10, TPE331-10AV and 26 more. Effective Nov 28, 2016
- [AD 2016-18-17](https://openairdocs.org/ad/2016-18-17): Compressor impeller · Honeywell International TPE331-10, TPE331-10AV, TPE331-10GP and 22 more. Effective Nov 4, 2016
- [AD 2015-18-03](https://openairdocs.org/ad/2015-18-03): Engine propeller shaft coupling failures · Honeywell International TPE331-10, TPE331-10R, TPE331-10U and 8 more. Effective Nov 13, 2015
- [AD 2012-02-06](https://openairdocs.org/ad/2012-02-06): First stage turbine disks · Honeywell International TPE331-10, TPE331-10AV, TPE331-10GP and 12 more. Effective Mar 15, 2012
- [AD 2011-18-51 R1](https://openairdocs.org/ad/2011-18-51-R1): Main shaft bearing · Honeywell International TPE331-1, TPE331-10, TPE331-10A and 82 more. Effective Oct 19, 2011
- [AD 2009-17-05](https://openairdocs.org/ad/2009-17-05): First stage turbine disks · Honeywell International TPE331-10, TPE331-10A, TPE331-10AV and 20 more. Effective Sep 1, 2009
- [AD 2006-14-03](https://openairdocs.org/ad/2006-14-03): New flight cycle counting method for first, second, and third-stage turbine rotors · Honeywell International TPE331-1, TPE331-10, TPE331-10A and 48 more. Effective Aug 9, 2006
- [AD 2004-09-29](https://openairdocs.org/ad/2004-09-29): First Stage Turbine Disks · Honeywell International TPE331-10, TPE331-10A, TPE331-10AV and 20 more. Effective Jun 15, 2004
- [AD 2002-25-02](https://openairdocs.org/ad/2002-25-02): First stage compressors implellers · Honeywell International TPE331-10, TPE331-10A, TPE331-10AV and 35 more. Effective Jan 21, 2003
- [AD 2002-21-15](https://openairdocs.org/ad/2002-21-15): Second stage turbine stator inner seal support · Honeywell International TPE331-1, TPE331-2, TPE331-2UA and 9 more. Effective Nov 26, 2002
- [AD 2002-12-09](https://openairdocs.org/ad/2002-12-09): Spectrometric Oil Analysis Program (SOAP) Sampling of Oil and Filter, Gearbox Components · Honeywell International TPE331-11U, TPE331-12B, TPE331-12JR and 3 more. Effective Jul 3, 2002
- [AD 2001-21-02](https://openairdocs.org/ad/2001-21-02): Airplane Flight Manual--Electronic Engine Controls · Honeywell International TPE331-10N, TPE331-12B and TPE331-8. Effective Nov 19, 2001
- [AD 98-12-09](https://openairdocs.org/ad/98-12-09): Fuel Manifold · Honeywell International TPE331-10, TPE331-10A, TPE331-10AV and 29 more. Effective Aug 7, 1998
- [AD 98-04-15](https://openairdocs.org/ad/98-04-15): Turbine Stators · Honeywell International TPE331-1, TPE331-2, TPE331-2UA and 9 more. Effective Apr 27, 1998
- [AD 97-15-10](https://openairdocs.org/ad/97-15-10): Engine Inlet Ice Protection · Honeywell International TPE331-10, TPE331-10A, TPE331-10AV and 39 more. Effective Sep 22, 1997
- [AD 95-16-08](https://openairdocs.org/ad/95-16-08): Life Limited Turbine Components · Honeywell International TPE331-1, TPE331-10, TPE331-10A and 62 more. Effective Sep 5, 1995
- [AD 94-26-07](https://openairdocs.org/ad/94-26-07): Fuel Control Governor Drive · Honeywell International TPE331-10, TPE331-10A, TPE331-10B and 32 more. Effective Apr 18, 1995
- [AD 94-09-08](https://openairdocs.org/ad/94-09-08): Third Stage Stator Turbine Assemblies · Honeywell International TPE331-1, TPE331-2, TPE331-2UA and 7 more. Effective May 20, 1994
- [AD 93-15-11](https://openairdocs.org/ad/93-15-11): Propeller Pitch Control (PPC) Gasket · Honeywell International TPE331-1, TPE331-10, TPE331-10A and 58 more. Effective Sep 7, 1993
- [AD 92-26-08](https://openairdocs.org/ad/92-26-08): Third Stage Stator Assemblies · Honeywell International TPE331-1, TPE331-2, TPE331-2UA and 7 more. Effective Jul 15, 1993
- [AD 93-05-09](https://openairdocs.org/ad/93-05-09): Third Stage Turbine Stator Assemblies · Honeywell International TPE331-1, TPE331-2, TPE331-2UA and 9 more. Effective Jun 28, 1993
- [AD 93-02-01](https://openairdocs.org/ad/93-02-01): Stratoflex Fuel Manifold Assemblies · Honeywell International TPE331-10, TPE331-10A, TPE331-10B and 21 more. Effective Mar 18, 1993
- [AD 89-07-07 R1](https://openairdocs.org/ad/89-07-07-R1): Oil Scavenge Pump Assembly · Honeywell International TPE331-1, TPE331-10, TPE331-10R and 26 more. Effective Oct 30, 1989
- [AD 86-08-06 R1](https://openairdocs.org/ad/86-08-06-R1): Second Stage Turbine Rotor Assembly · Honeywell International TPE331-25AA, TPE331-25AB, TPE331-25DA and 7 more. Effective Dec 21, 1987
- [AD 84-10-06 R1](https://openairdocs.org/ad/84-10-06-R1): Fuel Pump Assemblies · Honeywell International TPE331-1, TPE331-10, TPE331-10B and 45 more. Effective Dec 26, 1984
- [AD 84-01-04](https://openairdocs.org/ad/84-01-04): Third Stage Turbine Wheels · Honeywell International TPE331-1, TPE331-1U, TPE331-1UA and 11 more. Effective Jan 25, 1984
- [AD 73-26-07 R3](https://openairdocs.org/ad/73-26-07-R3): Fuel Pump Shaft Internal Drive Splines · Honeywell International TPE331-1, TPE331-1U, TPE331-1UA and 39 more. Effective Jul 31, 1980
- [AD 78-25-08 R3](https://openairdocs.org/ad/78-25-08-R3): Turbine Rotor · Honeywell International TPE331-1, TPE331-1U, TPE331-1UA and 11 more. Effective Jun 12, 1980
- [AD 79-12-04](https://openairdocs.org/ad/79-12-04): Forged Third Stage Turbine Wheel Blade · Honeywell International TPE331-10. Effective May 10, 1979
- [AD 78-05-02](https://openairdocs.org/ad/78-05-02): Propeller Pitch Control Cam Follower Pin · Honeywell International TPE331-1, TPE331-1U, TPE331-1UA and 11 more. Effective Apr 5, 1979
- [AD 76-16-01](https://openairdocs.org/ad/76-16-01): Bearing Oil Transfer Tube · Honeywell International TPE331-1, TPE331-1U, TPE331-1UA and 11 more. Effective Aug 6, 1976
- [AD 75-10-05](https://openairdocs.org/ad/75-10-05): Torque Sensor Assembly Mounting Arm · Honeywell International TPE331-1, TPE331-2, TPE331-3U and 3 more. Effective Jul 11, 1975
- [AD 74-10-10](https://openairdocs.org/ad/74-10-10): Fuel Control Assembly Support Bracket · Honeywell International TPE331-1, TPE331-2, TPE331-3U and 2 more. Effective Jul 11, 1975
- [AD 74-24-05](https://openairdocs.org/ad/74-24-05): Propeller Pitch Control Sleeve Assembly · Honeywell International TPE331-3U, TPE331-3UW, TPE331-5 and 1 more. Effective Nov 26, 1974
- [AD 70-19-02](https://openairdocs.org/ad/70-19-02): High Speed Pinion Bearings · Honeywell International TPE331-1, TPE331-1U, TPE331-1UA and 3 more. Effective Feb 20, 1974
- [AD 71-05-07](https://openairdocs.org/ad/71-05-07): High Speed Pinion Assembly · Honeywell International TPE331-1, TPE331-1U, TPE331-1UA and 30 more. Effective Apr 8, 1972
- [AD 70-16-09](https://openairdocs.org/ad/70-16-09): High Speed Pinion Assembly · Honeywell International TPE331-3W
- [AD 70-04-04](https://openairdocs.org/ad/70-04-04): High Speed Pinion Retaining Nut · Honeywell International TPE331-1, TPE331-1U, TPE331-1UA 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 2018-02-14](https://openairdocs.org/ad/2018-02-14) (historical): Turbine Engine Combustion Section · Honeywell International TPE331-1, TPE331-10, TPE331-10AV and 38 more. Effective Feb 28, 2018
- [AD 2015-12-04](https://openairdocs.org/ad/2015-12-04) (historical): Fuel control unit (FCU) · Honeywell International TPE331-1, TPE331-10, TPE331-10AV and 26 more. Effective Jul 22, 2015
- [AD 2011-18-51](https://openairdocs.org/ad/2011-18-51) (historical): Main shaft bearing · Honeywell International TPE331-1, TPE331-10, TPE331-10A and 82 more
- [AD 2006-15-08](https://openairdocs.org/ad/2006-15-08) (historical): Woodward fuel control unit (FCU) assemblies · Honeywell International TPE331-1, TPE331-10, TPE331-10AV and 26 more. Effective Aug 24, 2006
- [AD 88-12-10](https://openairdocs.org/ad/88-12-10) (historical): Turbine Rotor · Honeywell International TPE331-10, TPE331-10R, TPE331-10U and 6 more. Effective Jun 6, 1988
- [AD 92-02-19 PL](https://openairdocs.org/ad/92-02-19-PL) (historical): Fuel Manifold Assembly Leak · Honeywell International TPE331-10, TPE331-10A, TPE331-10AV and 29 more
- [AD 91-04-02](https://openairdocs.org/ad/91-04-02) (historical): Third stage stator assembly · Honeywell International TPE331-1, TPE331-2, TPE331-2UA and 7 more
- [AD 90-21-01](https://openairdocs.org/ad/90-21-01) (historical): Third stage stator assembly · Honeywell International TPE331-1, TPE331-2, TPE331-2UA and 7 more

## Information bulletins (advisory) (4 in force)

- [SAIB NE-16-19](https://openairdocs.org/saib/NE-16-19): Turbine Engine Compressor Section  Stator Nozzle Distress. Issued Jul 22, 2016
- [SAIB NE-16-18](https://openairdocs.org/saib/NE-16-18): Power Lever  Loss of Power Control. Issued Jul 11, 2016
- [SAIB NE-06-70](https://openairdocs.org/saib/NE-06-70): . Issued Sep 25, 2006
- [SAIB NE-06-69](https://openairdocs.org/saib/NE-06-69): . Issued Sep 20, 2006

## NTSB investigations

None matched to N752A.

## FAA accident and incident reports

None matched to N752A.

## 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) (47)

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 (Sikorsky S-55)

- [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 SA4-181](https://openairdocs.org/stc/SA4-181): Installation of VIP Part No. 101-79 engine mounts. FTG, Inc
- [STC SR02704SE](https://openairdocs.org/stc/SR02704SE): Installation and maintenance of the Sunspot 36 and 46 series lights. AeroLED's Holdings LLC
- [STC SA02268CH](https://openairdocs.org/stc/SA02268CH): Installation of Airwolf Filter Corp. Air Oil Separator. Airwolf Filter Corporation
- [STC SR00359BO](https://openairdocs.org/stc/SR00359BO): Installation of Parmetheus Plus LED PAR36 and PAR46 taxi and landing lights. Whelen Aerospace Technologies
- [STC SA01282NY](https://openairdocs.org/stc/SA01282NY): Installation of Airwolf remote mounted engine oil filter kit AFC-K015 on aircraft powered by Pratt & Whitney radial reciprocating engine Series R-985, R-1340 and R-1830. Airwolf Filter Corporation
- [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 SR09229RC](https://openairdocs.org/stc/SR09229RC): Installation approval of a 5 blade main rotor system and the Air Research TSE331-10UA-511SW engine. Whisper Jet Inc
- [STC SA2693NM](https://openairdocs.org/stc/SA2693NM): Installation of Electronics International digital volt/amp gauges and accessories. Electronics International Inc
- [STC SH51WE](https://openairdocs.org/stc/SH51WE): Installation of George M. Adams Model DGA-2000 wheel assembly. Skybound Manufacturing Inc
- [STC SR01034AT](https://openairdocs.org/stc/SR01034AT): Installation of forward and aft facing seats and cabin interior. Whisper Jet, Inc
- [STC SR01274AT](https://openairdocs.org/stc/SR01274AT): Installation of cabin doors and windows. Whisper Jet, Inc
- [STC SH127WE](https://openairdocs.org/stc/SH127WE): Installation of AiResearch TSE-331-3U-303N engine and related changes. Whisper Jet Inc
- [STC SR09190RC](https://openairdocs.org/stc/SR09190RC): Installation of a National Flight Services TSE331-10UA-511SW turbine conversion. Orlando Aviation, Inc
- [STC SR09041RC](https://openairdocs.org/stc/SR09041RC): Installation of a fuselage left cabin door. Federico Helicopters Inc
- [STC SA1626NM PAGE 2](https://openairdocs.org/stc/SA1626NM%20PAGE%202): Installation of Electronics Int'l Digital EGT/CHT Instruments and accessories. (201 Series). Electronics International
- [STC SH770NW](https://openairdocs.org/stc/SH770NW): Installation of a weighing system. Onboard Systems
- [STC SA4302NM](https://openairdocs.org/stc/SA4302NM): Installation of Electronics Int'l digital automatic engine analyzer. Electronics International
- [STC SH150WE](https://openairdocs.org/stc/SH150WE): Installation of Chadwick electronic weighing system C-46. Onboard Systems
- [STC SH4-181](https://openairdocs.org/stc/SH4-181): Installation of VIP P/N 101-79 mounts. Vibration Isolation Products Corp
- [STC SH1775SO](https://openairdocs.org/stc/SH1775SO): Installation of Wright R-1300-3 engine. Orlando Heli Airways Inc
- [STC SH1599SO](https://openairdocs.org/stc/SH1599SO): Removal of main transmission oil cooler blower and associated parts. Orlando Heli Airways Inc
- [STC SH1523SO](https://openairdocs.org/stc/SH1523SO): Add approved fuels: unleaded automotive gasoline 87 minimum antiknock index and leaded automotive gasoline, 88 minimum antiknock index (RON & MON)/2. Intermixing with aviation gasoline also approved. Orlando Heli Airways Inc
- [STC SH449NW](https://openairdocs.org/stc/SH449NW): Installation of an electronic weighing system (for monitoring cargo weight). Measurement Systems Intl
- [STC SH271WE](https://openairdocs.org/stc/SH271WE): Installation of cabin-mounted spray tank and external spray booms for agricultural purposes. Helitec Corporation
- [STC SH1072SO](https://openairdocs.org/stc/SH1072SO): Installation of dust boot retainer rings (in rotor head dampers). Orlando Heli Airways Inc
- [STC SH71EA](https://openairdocs.org/stc/SH71EA): South Wind heater 8259-A. Laboratory for Electronics Inc

### Approved for the engine (AiResearch TPE331 series)

- [STC SE02538AK](https://openairdocs.org/stc/SE02538AK): Modification of Honeywell TPE331-12JR-702TT engine. TAE Aerospace (CTEC). Lists TPE331-12JR
- [STC SE03035AT](https://openairdocs.org/stc/SE03035AT): Installation of Royal Atlantic Aviation Engine Oil Filter Bypass Warning System, Kit P/N RAA2003-1-1. Reds Aircraft Service Inc. Lists TPE331-10N
- [STC SE00265AT](https://openairdocs.org/stc/SE00265AT): Install Ayres Fuel Manifold Purge Assembly Kit, P/N 21757-1 in accordance with "Installation Instructions - Ayres P/N 21757-1 Fuel Manifold Purge Assy-Kit" Dwg. No. 21757-1(1), Revision none, dated April 20, 1993, or later FAA approved revision. Thrush Aircraft Inc. Lists TPE331-1
- [STC SE2924SO](https://openairdocs.org/stc/SE2924SO): Installation of Garrett TPE-331-10 combustor and turbine in the TPE331-8 engine. National Flight Lakeland. Lists TPE331-8
- [STC SE01461NY](https://openairdocs.org/stc/SE01461NY): Propeller pitch control system modification. Hartzell HC-E4N-5D/D9690(B) propeller installed per STC SA01462NY. Not approved on serial numbers TC-398 through TC-418. Hartzell Propeller Inc. Lists TPE331-10UA
- [STC SE01604CH](https://openairdocs.org/stc/SE01604CH): Convert Honeywell TPE331-10AV-511B to a TPE331-10AV-511KA. National Flight Services, Inc. Lists TPE331-10AV
- [STC SE00229AT](https://openairdocs.org/stc/SE00229AT): Installation of Garrett TPE331-10 Combustor and Turbine in TPE331-6 engine. National Flight Services, Inc. Lists TPE331-6
- [STC SE00275AT](https://openairdocs.org/stc/SE00275AT): Installation of GarrettTPE331-10 combustor and turbine in the TPE331-5 engine. National Flight Services, Inc. Lists TPE331-5
- [STC SE00691CH](https://openairdocs.org/stc/SE00691CH): Modification of a turboprop engine to a turboshaft configuration by incorporation of AlliedSignal (Garrett) TSE331-3U turboshaft gearbox components and other associated changes. National Flight Services, Inc. Lists TPE331-10UA
- [STC SE383CH](https://openairdocs.org/stc/SE383CH): Modification of engines. National Flight Services, Inc. Lists TPE331-1
- [STC SE7547SW](https://openairdocs.org/stc/SE7547SW): Install Garrett P/N 865558-16 or865558-1E propeller pitch control cam. Peacock Joe N. Lists TPE331-25A
- [STC SE8029SW](https://openairdocs.org/stc/SE8029SW): Modify propeller pitch control, P/N 869130, by installing pitch control cam, Garrett P/N869386-1. Agri Jet Power, Inc. Lists TPE331-1
- [STC SE1725CE](https://openairdocs.org/stc/SE1725CE): Modification to replace torque pressure compensator with a plug for raw torque pressure indicating provision. Air Midwest, Inc. Lists TPE331-3UW
- [STC SE33WE](https://openairdocs.org/stc/SE33WE): Modification of: ( 1) Manual fuel valve and beta cams; (2) Fuel control linkage and propeller servo cam; and (3)Automatic control of bleed valve and engine starting functions; S/N P61801 only. Garrett Turbine Engine Company A Division of the Garrett Corporation. Lists TPE331-25D
- [STC SE35WE](https://openairdocs.org/stc/SE35WE): Modification of the fuel control, linkage to permit 75% r.p.m. for low ground idle. Garrett Turbine Engine Company Division of Garret Corporation. Lists TPE331-47
- [STC SE39WE](https://openairdocs.org/stc/SE39WE): Modification of the fuel control linkage to permit 75% r.p.m. for ground idle doe S/N 86001. Garrett Turbine Engine Company A Division of the Garrett Corporation. Lists TPE331-57
- [STC SE50WE](https://openairdocs.org/stc/SE50WE): One engine only. Modification of a Model TPE331-25DAL to. incorporate the engine components associated with a torque and temperature 1imitinq system in accordance with AiResearch Kit PIN 896642-1. An en9ine incorporating this kit is reidentified as a Model TPE331-25DALT . Garrett Turbine Engine Company Division of Garret Corporation. Lists TPE331-25DA
- [STC SE68WE](https://openairdocs.org/stc/SE68WE): Deletion of fireshield installation kit. West-Figueroa Trust. Lists TPE331-6
- [STC SE56WE](https://openairdocs.org/stc/SE56WE): Serial Numbers P-06012 AND P-06024: Installation of heated compressor inlet temperature sensor lines. AiResearch Manufacturing Company. Lists TPE331-5
- [STC SE38WE](https://openairdocs.org/stc/SE38WE): Modification of fuel control linkage to permit operation of 75% idle speed. S/N 61701 & 61702. Garrett Turbine Engine Company Division of Garret Corporation. Lists TPE331-55

## Related

- Other Sikorsky S-55 aircraft: https://openairdocs.org/model/sikorsky-s-55/aircraft.md
- The AiResearch TPE331 series engine: https://openairdocs.org/engine/airesearch-tpe331-series.md

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