# N421PR: 1975 Cessna 421C

- Status: Valid registration
- Airframe: [Cessna 421C](https://openairdocs.org/model/cessna-421c) (registry code 2076016, 8 seats)
- Engine: [Continental GTSIO-520-C](https://openairdocs.org/engine/continental-gtsio-520-c) (registry code 17035)
- Data sheets: [TCDS A7CE](https://openairdocs.org/tcds/A7CE) (Textron Aviation Inc.), [TCDS E7CE](https://openairdocs.org/tcds/E7CE) (Continental Aerospace Technologies, Inc.) (OpenAirDocs)
- Serial number: 421C0027
- Year built: 1975
- Type: Fixed wing multi engine
- Engine type: Reciprocating
- Airworthiness: Standard, normal
- Airworthiness date: January 27, 1976
- Certificate issued: December 19, 2012
- Expires: December 31, 2028
- Mode S code: A500AB
- Registered owner: [Personal Air LLC](https://openairdocs.org/faa-owner/PERSONAL%20AIR%20LLC)
- Location: [Wilmington, DE](https://openairdocs.org/faa-place/DE/Wilmington)
- Owner type: LLC
- Owner's area on the map: 39.7236° N, 75.5412° W: Placed by OpenAirDocs at the center of ZIP code 19801, within about a mile (OpenAirDocs). The owner's mailing address, not where the aircraft is based
- FAA registry: https://registry.faa.gov/AircraftInquiry/Search/NNumberResult?nNumberTxt=421PR
- Page: https://openairdocs.org/aircraft/N421PR

From the FAA registry file of October 22, 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): 54 in force

### Matched by airframe (Cessna 421C)

- [AD 2023-09-09](https://openairdocs.org/ad/2023-09-09): Exhaust Turbine System (Recip) · Aerostar PA-60-600 (Aerostar 600), PA-60-601 (Aerostar 601), PA-60-601P (Aerostar 601P) and 292 more. Effective Jul 17, 2023
- [AD 2023-10-02](https://openairdocs.org/ad/2023-10-02): Indicating/Recording System, Navigation · Boeing 18, 23, 35 and 1,060 more. Effective May 26, 2023
- [AD 2018-03-03 R1](https://openairdocs.org/ad/2018-03-03-R1): Fuselage · Textron 401, 401A, 401B and 13 more. Effective May 23, 2018
- [AD 2016-17-08](https://openairdocs.org/ad/2016-17-08): Elevator Tab Control System · Textron 310, 310A, 310B and 46 more. Effective Sep 12, 2016
- [AD 2006-16-18 R1](https://openairdocs.org/ad/2006-16-18-R1): Installing a warning placard on the TAWS/RMI · Airbus A300 B2-1A, A300 B2-1C, A300 B2-203 and 100 more. Effective Jul 18, 2008
- [AD 2005-20-25](https://openairdocs.org/ad/2005-20-25): Avionics bus circuit breaker switches · Cessna 401, 401A, 401B and 15 more. Effective Nov 9, 2005
- [AD 2004-25-16 R1](https://openairdocs.org/ad/2004-25-16-R1): Fuel regulator shutoff valve · Bombardier CL-215-1A10, CL-215-6B11 (CL-215T Variant), CL-215-6B11 (CL-415 Variant) and 64 more. Effective Jun 20, 2005
- [AD 2005-01-19](https://openairdocs.org/ad/2005-01-19): Mode S transponders · GARMIN International GTX 330D, GTX 330, GTX 33D and 830 more. Effective Feb 23, 2005
- [AD 2004-21-05](https://openairdocs.org/ad/2004-21-05): B-Seires Combustion Heaters · Bombardier CL-215-1A10, CL-215-6B11 (CL-215T Variant), CL-215-6B11 (CL-415 Variant) and 41 more. Effective Nov 19, 2004
- [AD 2001-23-17](https://openairdocs.org/ad/2001-23-17): GNS 430 units · Cessna 172, 182, 206 and 209 more. Effective Dec 28, 2001
- [AD 2000-01-16](https://openairdocs.org/ad/2000-01-16): Exhaust System · Cessna 320, 320-1, 320A and 28 more. Effective Feb 15, 2000
- [AD 98-25-02](https://openairdocs.org/ad/98-25-02): Top-mounted Antenna · Bell Helicopter Textron Canada 407, 172, 172A and 243 more. Effective Dec 22, 1998
- [AD 98-14-03](https://openairdocs.org/ad/98-14-03): Transponders · Cessna 172, 172A, 172B and 230 more. Effective Aug 16, 1998
- [AD 98-04-28](https://openairdocs.org/ad/98-04-28): AFM - Limitations Section - Icing · Cessna 310R, 335, 340A and 12 more. Effective Mar 13, 1998
- [AD 97-01-13](https://openairdocs.org/ad/97-01-13): Fuel, Oil and Hydraulic Hoses · Cessna 150, 150A, 150B and 232 more. Effective Feb 3, 1997
- [AD 96-12-22](https://openairdocs.org/ad/96-12-22): Full Flow Engine Oil Adapter · Bellanca CH-300 Pacemaker, 120, 140 and 361 more. Effective Jul 31, 1996
- [AD 95-09-13](https://openairdocs.org/ad/95-09-13): Fuel Inlet Float Valve · Cessna 402C, 404, 414A and 2 more. Effective Jun 14, 1995
- [AD 91-25-08 R1](https://openairdocs.org/ad/91-25-08-R1): Wing Front Spar Upper Caps · Cessna 421C and 425. Effective Nov 4, 1994
- [AD 92-16-18](https://openairdocs.org/ad/92-16-18): Passenger Seat Reinforcement · Cessna 401, 402, 402A and 9 more. Effective Sep 10, 1992
- [AD 90-02-13](https://openairdocs.org/ad/90-02-13): Main Landing Gear · Cessna 310, 310A, 310B and 40 more. Effective Feb 5, 1990
- [AD 87-21-02 R1](https://openairdocs.org/ad/87-21-02-R1): Fuel Filler Openings · Cessna 310D, 310E, 310F and 41 more. Effective Jun 16, 1989
- [AD 84-20-02](https://openairdocs.org/ad/84-20-02): Nose Landing Gear · Cessna 402C, 404, 414A and 3 more. Effective Nov 1, 1984
- [AD 84-03-04](https://openairdocs.org/ad/84-03-04): Windshield Installation Inspection · Cessna 414A, 421C and 425. Effective Feb 16, 1984
- [AD 80-20-06](https://openairdocs.org/ad/80-20-06): KFC-200 Flight Control System Modification Under STC SA1246CE · Cessna 421C with STC SA1246CE. Effective Oct 14, 1980
- [AD 80-17-04](https://openairdocs.org/ad/80-17-04): Fuel Flow Transducers · Aerosonic Fuel Flow Transducers, PA-60-600 (Aerostar 600), PA-60-601 (Aerostar 601) and 9 more. Effective Aug 13, 1980
- [AD 80-13-14](https://openairdocs.org/ad/80-13-14): Fuel Flow Transducer · Cessna 310R, 335, 340A and 4 more. Effective Jul 22, 1980
- [AD 78-13-05](https://openairdocs.org/ad/78-13-05): Improperly Installed Seats · Cessna 340, 340A, 402B and 7 more. Effective Jul 5, 1978
- [AD 78-11-05](https://openairdocs.org/ad/78-11-05): Autopilot Actuator · Cessna 210M, 310R, 340A and 9 more. Effective Jun 5, 1978
- [AD 77-09-02](https://openairdocs.org/ad/77-09-02): Windshield Inspection and Repair · Cessna 421B and 421C. Effective May 9, 1977
- [AD 76-13-07](https://openairdocs.org/ad/76-13-07): Fork Bolts · Cessna 401, 401A, 401B and 11 more. Effective Jul 7, 1976
- [AD 76-07-07](https://openairdocs.org/ad/76-07-07): Fuel Leakage · Cessna 421C. Effective Apr 12, 1976
- [AD 72-11-05](https://openairdocs.org/ad/72-11-05): Auxiliary Fuel Cell Leaks · Cessna 411, 411A, 421 and 3 more. Effective Jun 2, 1972
- [AD 72-03-07](https://openairdocs.org/ad/72-03-07): Landing Gear Failure · Cessna 310, 310A, 310B and 30 more. Effective Feb 9, 1972

### Matched by engine (Continental GTSIO-520-C)

- [AD 2023-05-16](https://openairdocs.org/ad/2023-05-16): Reciprocating Engine Power Section · Continental Aerospace Technologies GTSIO-520-C, GTSIO-520-D, GTSIO-520-H and 147 more. Effective Mar 15, 2023
- [AD 2023-02-12](https://openairdocs.org/ad/2023-02-12): Engine Air Intake System · Continental Aerospace Technologies GTSIO-520-C, GTSIO-520-D, GTSIO-520-E and 127 more. Effective Feb 17, 2023
- [AD 2022-16-03](https://openairdocs.org/ad/2022-16-03): Engine (RECIPROCATING) · Continental Aerospace Technologies GTSIO-520-C, GTSIO-520-D, GTSIO-520-F and 236 more. Effective Aug 15, 2022
- [AD 2020-16-11](https://openairdocs.org/ad/2020-16-11): SUMMARY: Reciprocating Cylinder Section · Continental Aerospace Technologies GTSIO-520-C, GTSIO-520-D, GTSIO-520-H and 23 more. Effective Sep 21, 2020
- [AD 2016-16-12](https://openairdocs.org/ad/2016-16-12): Cylinder assemblies · Continental Motors LTSIO-520-AE, TSIO-520-A, TSIO-520-AE and 89 more. Effective Sep 15, 2016
- [AD 2012-03-06](https://openairdocs.org/ad/2012-03-06): Fuel servo diaphragm · Continental Motors 6-260-A, 6-285-A, 6-285-B and 482 more. Effective Feb 24, 2012
- [AD 2010-11-04](https://openairdocs.org/ad/2010-11-04): Hydraulic lifters · Continental Motors FSO-470-A, GIO-470-A, GTSIO-520-C and 190 more. Effective Jun 16, 2010
- [AD 2007-05-15](https://openairdocs.org/ad/2007-05-15): Starter adapter assembly · Continental Motors GTSIO-520-C, GTSIO-520-D, GTSIO-520-E and 6 more. Effective Apr 16, 2007
- [AD 2004-08-10](https://openairdocs.org/ad/2004-08-10): Serial-numbered (SN) cylinders · Modify Teledyne Continental TSIO-520-NB engine (RAM Aircraft Limited Partnership STC SE09104SC or 4 others). Effective May 5, 2004
- [AD 99-19-01](https://openairdocs.org/ad/99-19-01): No. 2 and No. 5 Crankshaft Inspections · Continental Motors GTSIO-520-C, GTSIO-520-D, GTSIO-520-E and 127 more. Effective Sep 30, 1999
- [AD 98-17-11](https://openairdocs.org/ad/98-17-11): Crankshafts · Continental Motors A-65-3, A-65-8, A75-8 and 90 more. Effective Oct 19, 1998
- [AD 95-21-15](https://openairdocs.org/ad/95-21-15): Aviation Gasoline · Continental Motors A-65-8, C85-12F, C85-12FJ and 77 more. Effective Nov 28, 1995
- [AD 93-10-02](https://openairdocs.org/ad/93-10-02): Missing Cylinder Valve Retainer Key · Continental Motors GTSIO-520-C, GTSIO-520-D, GTSIO-520-E and 180 more. Effective Aug 12, 1993
- [AD 91-19-03](https://openairdocs.org/ad/91-19-03): Oil Filter · Continental Motors 6-285-A, 6-285-B, 6-285-BA and 169 more. Effective Sep 29, 1991
- [AD 88-03-06](https://openairdocs.org/ad/88-03-06): Oil Filter · Continental Motors GTSIO-520-C, GTSIO-520-D, GTSIO-520-E and 155 more. Effective Apr 15, 1988
- [AD 86-13-04 R3](https://openairdocs.org/ad/86-13-04-R3): Cylinder Assemblies · Continental Motors GTSIO-520-C, GTSIO-520-D, GTSIO-520-H and 44 more. Effective Feb 24, 1988
- [AD 81-24-06](https://openairdocs.org/ad/81-24-06): Engine Driven Fuel Pumps · Continental Motors GTSIO-520-C, GTSIO-520-D, GTSIO-520-E and 51 more. Effective Nov 23, 1981
- [AD 79-05-09](https://openairdocs.org/ad/79-05-09): Oil Pump Assembly Or Oil Pressure Relief Valve Screw And/Or Plunger · Teledyne Continental Motors 6-285-CA, GTSIO-520-C, GTSIO-520-D and 60 more. Effective Mar 12, 1979
- [AD 75-09-13](https://openairdocs.org/ad/75-09-13): Turbocharger Oil Inlet Adapter · Continental Motors GTSIO-520-C, GTSIO-520-D, GTSIO-520-F and 9 more. Effective Apr 24, 1975
- [AD 80-09-11](https://openairdocs.org/ad/80-09-11): Starter Torsional Damper/Starter Gear Shaft · Continental Motors GTSIO-520-C, GTSIO-520-D, GTSIO-520-E and 6 more
- [AD 77-13-22](https://openairdocs.org/ad/77-13-22): Crankcase Cracks · Continental Motors GTSIO-520-C, GTSIO-520-D, GTSIO-520-F and 22 more

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

- [AD 2018-03-03](https://openairdocs.org/ad/2018-03-03) (historical): Fuselage · Textron 401, 401A, 401B and 13 more. Effective Feb 28, 2018
- [AD 2016-07-24](https://openairdocs.org/ad/2016-07-24) (historical): Elevator Tab Control System · Textron 310, 310A, 310B and 46 more. Effective Apr 26, 2016
- [AD 75-23-08 R5](https://openairdocs.org/ad/75-23-08-R5) (historical): Engine Exhaust System · Cessna Aircraft Company, The 320 Model or Series (all), 340 Model or Series (all), 401 Model or Series (all) and 12 more. Effective Nov 4, 1986
- [AD 2023-04-08](https://openairdocs.org/ad/2023-04-08) (historical): Reciprocating Engine Power Section · Continental Aerospace Technologies GTSIO-520-C, GTSIO-520-D, GTSIO-520-H and 141 more. Effective Feb 23, 2023
- [AD 2009-24-52](https://openairdocs.org/ad/2009-24-52) (historical): Hydraulic lifters · Continental Motors FSO-470-A, GIO-470-A, GTSIO-520-C and 192 more
- [AD 2009-24-51](https://openairdocs.org/ad/2009-24-51) (historical): Hydraulic lifters · Teledyne Continental Motors FSO-470-A, GIO-470-A, GTSIO-520-C and 156 more
- [AD 2005-20-04](https://openairdocs.org/ad/2005-20-04) (historical): Starter adapter assembly · Teledyne Continental Motors GTSIO-520-C, GTSIO-520-D, GTSIO-520-E and 6 more. Effective Nov 1, 2005
- [AD 94-14-12](https://openairdocs.org/ad/94-14-12) (historical): Octane Aviation Gasoline · Teledyne Continental Motors A-65-8, C85-12, E185-11 and 68 more

## Information bulletins (advisory) (16 in force)

- [SAIB CE-13-27R1](https://openairdocs.org/saib/CE-13-27R1): Flight Controls  Frayed Flap Extend Cables. Issued Jan 5, 2022
- [SAIB AIR-21-20](https://openairdocs.org/saib/AIR-21-20): TE FLAP CONTROL SYSTEM, Flight Controls –Flap Cable Tension. Issued Dec 16, 2021
- [SAIB CE-14-11R1](https://openairdocs.org/saib/CE-14-11R1): Landing Gear; Nose Landing Gear Trunnions. Issued Sep 23, 2015
- [SAIB CE-14-19](https://openairdocs.org/saib/CE-14-19): Landing Gear; Main Landing Gear (MLG) Torque Link. Issued May 30, 2014
- [SAIB CE-13-22](https://openairdocs.org/saib/CE-13-22): Electrical Power System  Circuit Breaker Switch. Issued Mar 13, 2013
- [SAIB CE-11-29R1](https://openairdocs.org/saib/CE-11-29R1): Flight Control System. Issued Sep 27, 2011
- [SAIB CE-10-01](https://openairdocs.org/saib/CE-10-01): Fuel: Fuel Tank Selector Valve Systems. Issued Oct 5, 2009
- [SAIB CE-03-17](https://openairdocs.org/saib/CE-03-17): . Issued Jan 13, 2003
- [SAIB ACE-99-06](https://openairdocs.org/saib/ACE-99-06): . Issued Nov 17, 1998
- [SAIB ACE-99-05](https://openairdocs.org/saib/ACE-99-05): . Issued Nov 17, 1998
- [SAIB NE-18-16](https://openairdocs.org/saib/NE-18-16): POWERPLANT  Alternator Drive Coupling. Issued Jun 20, 2018
- [SAIB NE-16-13](https://openairdocs.org/saib/NE-16-13): Powerplant - Prohibited use of sealant. Issued Mar 8, 2016
- [SAIB NE-13-15](https://openairdocs.org/saib/NE-13-15): Engine Controls: Continental Motors, Inc. (CMI) Throttle and Mixture Control Levers. Issued Feb 8, 2013
- [SAIB NE-13-04](https://openairdocs.org/saib/NE-13-04): Continental Motors, Inc. (CMI) Connecting Rod Piston Pin Bushing Inspection. Issued Oct 31, 2012
- [SAIB NE-10-09](https://openairdocs.org/saib/NE-10-09): Reciprocating Engine Power Section: Hydraulic Valve Lifters. Issued Nov 20, 2009
- [SAIB NE-09-08](https://openairdocs.org/saib/NE-09-08): Reciprocating Engine Cylinder Section. Issued Jan 30, 2009
- [SAIB CE-14-11](https://openairdocs.org/saib/CE-14-11) (historical): Landing Gear; Nose Landing Gear Trunnions. Issued Feb 25, 2014
- [SAIB CE-11-29](https://openairdocs.org/saib/CE-11-29) (historical): Flight Control System. Issued Apr 22, 2011

## NTSB investigations

None matched to N421PR.

## FAA accident and incident reports

None matched to N421PR.

## Service difficulty reports (1)

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 K4SA200901](https://openairdocs.org/sdr/K4SA200901), Jun 24, 2009: DISTRIBUTOR GEAR. BROKEN. AFTER LEVEL OFF FOR CRUISE, A VIBRATION OR BUFFET WAS NOTED. ALL ENGINE TEMPS AND INDICATIONS APPEARED NORMAL. WAS UNABLE TO IDENTIFY WHICH ENGINE WAS CAUSING V

## STCs that may be installed (OpenAirDocs) (279, first 50)

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 (Cessna 421C)

- [STC SA01800SE](https://openairdocs.org/stc/SA01800SE): Fabrication and installation of new or replacement of existing instrument panel lights dimmer control. TCW Technologies, LLC
- [STC SA01861SE](https://openairdocs.org/stc/SA01861SE): Fabrication and installation of Landing Light Controller. TCW Technologies, LLC
- [STC SA01844WI](https://openairdocs.org/stc/SA01844WI): Installation of Garmin GFC 600 Automatic Flight Control System. Garmin International Inc
- [STC SA02279AT](https://openairdocs.org/stc/SA02279AT): Installation of a Boom Beam bulb, starter, and ballast. Whelen Aerospace Technologies
- [STC SA04837NY](https://openairdocs.org/stc/SA04837NY): Installation of AeroLED's Holdings, LLC., position lights, navigation lights, strobe lights and beacon lights. AeroLED's Holdings, LLC
- [STC SA02019SE-D](https://openairdocs.org/stc/SA02019SE-D): Installation of Garmin Model GTN 625/635/650; 725/750 Navigation System. Garmin International Inc
- [STC SA00079NY](https://openairdocs.org/stc/SA00079NY): Installation of Airwolf remote mounted engine oil filter kit AFC-K008 on single and multi engine fixed wing light aircraft incorporating Teledyne Continental reciprocating engines of 450 horsepower or less. Airwolf Filter Corporation
- [STC SA02511SE](https://openairdocs.org/stc/SA02511SE): Installation of replacement fuel quantity indicator sending unit(s). CiES Inc
- [STC SA5581SW](https://openairdocs.org/stc/SA5581SW): Installation of ALCOR true-flow/ totalizer system. Alcor LLC. Lists 421 Series
- [STC SA02731SE](https://openairdocs.org/stc/SA02731SE): Installation of Luma Technologies LT-4300 Series LED Display Panel and/or LT-4302 LED Gear Status Annunciator. Luma Technologies LLC
- [STC SA02738CH](https://openairdocs.org/stc/SA02738CH): Installation of L-3 Communications Avionics Systems. Acron Aviation Inc
- [STC SA04046CH PAGE 1](https://openairdocs.org/stc/SA04046CH%20PAGE%201): Installation of L-3 GENESIS (TM) Electronic Standby Instrument System (ESI-500/MAG-500). Acron Aviation Inc
- [STC SA02386AK](https://openairdocs.org/stc/SA02386AK): Replacement of existing landing and/or taxi light reflector and bulbs with Light Emitting Diode (LED) lighting systems. AeroLED's Holding LLC
- [STC SA02658SE](https://openairdocs.org/stc/SA02658SE): Installation of Garmin GI 275 Multi-Function Display System. Garmin International Inc
- [STC SA02571SE](https://openairdocs.org/stc/SA02571SE): Installation of Garmin G500/G600 TXi Integrated Avionics System (Primary Flight Display, Multi-Function Display, and Engine Indicating System Display). Garmin International Inc
- [STC SA02532AT](https://openairdocs.org/stc/SA02532AT): Installation of subject Michelin tires on appropriate aircraft. For Michelin 5, 6, 8, and 10-inch rim diameter tires on General Aviation Aircraft. Michelin North America Inc
- [STC SA00756DE](https://openairdocs.org/stc/SA00756DE): Installation of Automatic Dependent Surveillance Broadcast (ADS-B) Out Equipment using a Trig Avionics TT22 Transponder and an approved Global Positioning System (GPS) Position Sensor. Peregrine
- [STC SA02010WI](https://openairdocs.org/stc/SA02010WI): Installation of the Mid-Continent Instruments & Avionics MD23 FLEX Custom Function Display (CFD). Mid-Continent Instruments and Avionics
- [STC SA197GL](https://openairdocs.org/stc/SA197GL): Install Cleveland conversion kit P/N 199-76. Kaman Corporation Aircraft Wheel and Brake LLC
- [STC SA01967WI](https://openairdocs.org/stc/SA01967WI): Use of GAMI G100UL High Octane Unleaded Avgas. General Aviation Modifications Inc
- [STC SA02203AK](https://openairdocs.org/stc/SA02203AK): Installation of FlightLogic Synthetic Vision Electronic Flight Information System (EFIS-SV). Genesys Aerosystems Inc
- [STC SA02254AK](https://openairdocs.org/stc/SA02254AK): Installation of "Single Screen", "2 or 3 Screen", "Dual Screen", or "4 or 6 screen". Genesys Aerosystems Inc
- [STC SA02444AK](https://openairdocs.org/stc/SA02444AK): Approval of the L-3 Communications NGT 9000/9000R ADS-B system installed. ADS-B Technologies LLC
- [STC SA4270SW](https://openairdocs.org/stc/SA4270SW): Mount collision avoidance lights in engine nacelle. Johnson Aviation Products
- [STC SA04195NY](https://openairdocs.org/stc/SA04195NY): Installation of the KFC 230 Aerocruze Automatic Flight Control System (FCS) upgraded from KFC 200 FCS. Honeywell International Inc. (Bendix King)
- [STC SA09856AC](https://openairdocs.org/stc/SA09856AC): Installation of BendixKing Aerowave 100 In-flight Data Link System for non-essential, non-required aircraft Cabin Systems & Equipments. Honeywell International Inc (Bendix King)
- [STC SA11174SC PAGE 1](https://openairdocs.org/stc/SA11174SC%20PAGE%201): Installation of BendixKing by Honeywell KSN 770 and KSN 765 WAAS LPV approach capable nav/comm systems. Honeywell International Inc (Bendix King)
- [STC SA02265SE](https://openairdocs.org/stc/SA02265SE): Installation of a camera housing. Airborne Sensor LLC
- [STC SA01316LA](https://openairdocs.org/stc/SA01316LA): Installation of Sandel Avionics Terrain Awareness and Warning System. Sandel Avionics LLC
- [STC SA01815LA](https://openairdocs.org/stc/SA01815LA): Installation of Sandel Avionics SN3500 Electronic Horizontal Situation Indicator (EHSI). Sandel Avionics LLC
- [STC SA10236SC](https://openairdocs.org/stc/SA10236SC): Installation of a GDC 31 Roll Steering Converter. DAC International Inc
- [STC SA03317CH](https://openairdocs.org/stc/SA03317CH): Installation of Max-Viz EVS-600 Enhanced Vision System. PECO Inc
- [STC SA02268CH](https://openairdocs.org/stc/SA02268CH): Installation of Airwolf Filter Corp. Air Oil Separator. Airwolf Filter Corporation
- [STC SA00997WI-D](https://openairdocs.org/stc/SA00997WI-D): Installation of Bendix/King KFC 225 Automatic Flight Control System. For Model 421C, serial numbers 421C0401 and after. Honeywell International Inc
- [STC SA00998WI-D](https://openairdocs.org/stc/SA00998WI-D): Installation of Bendix/King KMD 550/850 Multi-Function Display, with optional KLN 94 Global Positioning System, KGP 560 General Aviation Enhanced Ground Proximity Warning System, RDR 2000 Weather Radar System and KMH 880 Multi-Hazard Awareness System or KTA 870 Traffic Awareness System. Honeywell International Inc
- [STC SA1246CE](https://openairdocs.org/stc/SA1246CE): Installation of King KFC-200 2 axis (3 optional) flight control system with a KI-255 (or -256) flight command indicator or a KG-258 Attitude Horizon Gyro with a KC-292 Mode Controller. Honeywell International Inc
- [STC SA1521CE-D](https://openairdocs.org/stc/SA1521CE-D): Installation of King KFC 250 flight control system (3 axis) using 3-inch or 4-inch indicators. Honeywell International Inc
- [STC SA1526CE-D](https://openairdocs.org/stc/SA1526CE-D): Installation of King KAS 297 Altitude Selector Option. Honeywell International Inc
- [STC SA01452CH](https://openairdocs.org/stc/SA01452CH): Installation of an air ambulance conversion kit. Med-Pac Inc
- [STC SA01714WI](https://openairdocs.org/stc/SA01714WI): Installation of a Garmin transponders: (a) GTX 330/330D/33/33D with ADS-B Out functionality; (b) GTX 335/335R/345/345R with ADS-B Out and In functionality; or (c) GTX 335R/345R with ADS-B Out functionality in select airplanes installed with G950/G1000 systems. Garmin International Inc
- [STC SA01750SE](https://openairdocs.org/stc/SA01750SE): Fabrication and Installation of Dahlia Doubler. Fliegen Works Inc
- [STC SA01751SE](https://openairdocs.org/stc/SA01751SE): Fabrication and Installation of Panida Doubler. Fliegen Works Inc
- [STC SA01752SE](https://openairdocs.org/stc/SA01752SE): Fabrication and Installation of Panida Doubler. Fliegen Works Inc
- [STC SA8RM](https://openairdocs.org/stc/SA8RM): Installation of a vapor cycle air-conditioning system. Air Comm Corporation
- [STC SA00344BO PAGE 1](https://openairdocs.org/stc/SA00344BO%20PAGE%201): Installation of Parmetheus Plus LED PAR36 and PAR46 taxi and landing lights. Whelen Aerospace Technologies
- [STC SA00057SE](https://openairdocs.org/stc/SA00057SE): Installation of emergency medical stretcher, oxygen, and electrical systems. LifePort LLC
- [STC SA02838AT](https://openairdocs.org/stc/SA02838AT): Installation of a Strobe Light System. Reds Aircraft Service Inc
- [STC SA00571SE](https://openairdocs.org/stc/SA00571SE): Replacement of certain BF Goodrich pneumatic deicer boots. SMR Technologies Inc
- [STC SA01213CH](https://openairdocs.org/stc/SA01213CH): Install air ambulance conversion in accordance with Spectrum Aeromed Inc. Drawings as listed on AML SA01213CH, or later FAA approved revision. Spectrum Aeromed LLC dba Spectrum Aeromed
- [STC SA00744DE](https://openairdocs.org/stc/SA00744DE): Installation of the Automatic Dependent Surveillance Broadcast (ADS-B) Out Equipment using a Trig Avionics TT31 Transponder and an approved position sensor. Peregrine

All 279: https://openairdocs.org/aircraft/N421PR/stcs.md

## Related

- Other Cessna 421C aircraft: https://openairdocs.org/model/cessna-421c/aircraft.md
- The Continental GTSIO-520-C engine: https://openairdocs.org/engine/continental-gtsio-520-c.md

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