# N172PA: Cessna 172N

- Status: Valid registration
- Airframe: [Cessna 172N](https://openairdocs.org/model/cessna-172n) (registry code 2072434, 4 seats)
- Engine: [Porsche PFM3200N03](https://openairdocs.org/engine/porsche-pfm3200n03) (registry code 51002)
- Data sheets: [TCDS 3A12](https://openairdocs.org/tcds/3A12) (Textron Aviation Inc.), [TCDS E23NE](https://openairdocs.org/tcds/E23NE) (Porsche K.-G. Dr. Ing.h.c.F.) (OpenAirDocs)
- Serial number: 17269467
- Type: Fixed wing single engine
- Engine type: Reciprocating
- Airworthiness: Standard, normal
- Airworthiness date: September 17, 1990
- Certificate issued: June 4, 2020
- Expires: June 30, 2027
- Mode S code: A121E1
- Registered owner: [Roseville Aviation LLC](https://openairdocs.org/faa-owner/ROSEVILLE%20AVIATION%20LLC)
- Location: [Roxboro, NC](https://openairdocs.org/faa-place/NC/Roxboro)
- Owner type: LLC
- Owner's area on the map: 36.3990° N, 78.9751° W: Placed by OpenAirDocs at the center of ZIP code 27573, within about 2 miles (OpenAirDocs). The owner's mailing address, not where the aircraft is based
- FAA registry: https://registry.faa.gov/AircraftInquiry/Search/NNumberResult?nNumberTxt=172PA
- Page: https://openairdocs.org/aircraft/N172PA

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): 42 in force

### Matched by airframe (Cessna 172N)

- [AD 2024-14-03](https://openairdocs.org/ad/2024-14-03): Autopilot System · Garmin GFC 500 Autopilot (STC SA01866WI). Effective Aug 20, 2024
- [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 2022-03-15](https://openairdocs.org/ad/2022-03-15): Fuel Quantity Indicator · Garmin G3X Touch Electronic Flight Instrument System (STC SA01899WI or SA02658SE). Effective Mar 21, 2022
- [AD 2020-18-01](https://openairdocs.org/ad/2020-18-01): Fuselage · Textron 172N, 172P, 172Q and 62 more. Effective Nov 12, 2020
- [AD 2011-10-09](https://openairdocs.org/ad/2011-10-09): Seat Rails and Roller Housing Inspections · Cessna 150A, 150B, 150C and 221 more. Effective Jun 17, 2011
- [AD 2011-06-02](https://openairdocs.org/ad/2011-06-02): Engine · TAE 125-01 Engine Installation (Technify Motors STC SA01303WI). Effective May 26, 2011
- [AD 2008-26-10](https://openairdocs.org/ad/2008-26-10): Alternate static air source selector valve · Cessna 172, 172A, 172B and 179 more. Effective Jan 5, 2009
- [AD 2008-02-18](https://openairdocs.org/ad/2008-02-18): Pick-up collar support and nylon screws · BRS-172 parachute recovery system (Ballistic Recovery Systems STC SA01679CH or SA01999CH). Effective Feb 28, 2008
- [AD 2006-03-08](https://openairdocs.org/ad/2006-03-08): Vacuum pumps · Aero Advantage 14-19, 14-19-2, 14-19-3 and 299 more. Effective Mar 10, 2006
- [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 2001-23-03](https://openairdocs.org/ad/2001-23-03): Forward Door Post · Cessna 172N, 172P, 172RG and 5 more. Effective Dec 27, 2001
- [AD 2000-06-01](https://openairdocs.org/ad/2000-06-01): Fuel Strainer Assembly · Cessna 150F, 150G, 150H and 163 more. Effective May 5, 2000
- [AD 98-21-21 R1](https://openairdocs.org/ad/98-21-21-R1): Electric Inflatable Door Seals · Cessna 17-30, 17-30A, 17-31 and 267 more. Effective May 1, 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 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 96-09-06](https://openairdocs.org/ad/96-09-06): Air Filter Assemblies · Maule Aerospace Technology 7ACA, 7ECA, 7FC and 180 more. Effective Jun 7, 1996
- [AD 90-06-03 R1](https://openairdocs.org/ad/90-06-03-R1): Exhaust Heater/Muffler Assembly · Cessna 172, 172A, 172B and 16 more. Effective Mar 27, 1991
- [AD 79-10-14 R1](https://openairdocs.org/ad/79-10-14-R1): Fuel Tank Venting · Cessna 140A, 150, 150A and 172 more. Effective May 30, 1988
- [AD 86-24-07](https://openairdocs.org/ad/86-24-07): Engine Controls Installation · Cessna 150C, 150D, 150E and 142 more. Effective Jan 7, 1987
- [AD 83-22-06](https://openairdocs.org/ad/83-22-06): Aileron Hinge Pin · Cessna 152, 172N, 172P and 18 more. Effective Nov 8, 1983
- [AD 83-17-06](https://openairdocs.org/ad/83-17-06): Aileron Balance Weights · Flap actuated aileron droop system (Sierra Industries STC SA1382WE or 5 others). Effective Sep 1, 1983
- [AD 83-10-03](https://openairdocs.org/ad/83-10-03): Control Wheel Yoke Guide Modification · Cessna 172M, 172N, 172P and 17 more. Effective Jun 30, 1983
- [AD 82-07-02](https://openairdocs.org/ad/82-07-02): Engine Crankcase Breather · Lycoming O-360-A1A engine and Hartzell HC-C2YK-1B/7666A-2… (Avcon Industries STC SA1324CE or 14 others). Effective Apr 8, 1982
- [AD 80-25-07 R1](https://openairdocs.org/ad/80-25-07-R1): Oil Coolers · American Champion 7ECA, 7GCAA, 7GCBC and 39 more. Effective Sep 24, 1981
- [AD 81-16-09](https://openairdocs.org/ad/81-16-09): Elevator Control System · Cessna 172N, 172P, 172RG and 17 more. Effective Aug 13, 1981
- [AD 81-05-01](https://openairdocs.org/ad/81-05-01): Fuel Tank Capacity · Cessna 152, 172N, 172P and 3 more. Effective Mar 2, 1981
- [AD 80-06-03](https://openairdocs.org/ad/80-06-03): Wing Flap Cable Clamp · Cessna 150M, 152, 172N and 3 more. Effective Apr 21, 1980
- [AD 79-08-03](https://openairdocs.org/ad/79-08-03): Electrical System · Cessna 120, 140, 140A and 152 more. Effective Jun 6, 1979
- [AD 77-12-08](https://openairdocs.org/ad/77-12-08): External Electrical Ground Power Receptacle · Cessna 172M, 172N, 177B and 19 more. Effective Jun 27, 1977
- [AD 77-02-09](https://openairdocs.org/ad/77-02-09): Wing Flap System · Cessna 150, 150A, 150B and 61 more. Effective Feb 3, 1977
- [AD 76-21-06](https://openairdocs.org/ad/76-21-06): Loss of Engine Oil · Cessna 172M, 172N, 177B and 1 more. Effective Oct 26, 1976
- [AD 74-06-02](https://openairdocs.org/ad/74-06-02): AVCON Mufflers · Lycoming 150 and160 hp Model O-320-( ) engine (Williams Robert or Barbara STC SA750CE or 3 others). Effective Mar 18, 1974
- [AD 74-04-01](https://openairdocs.org/ad/74-04-01): Aft Fuselage Bulkhead Assembly · Cessna 172, 172A, 172B and 16 more. Effective Feb 12, 1974
- [AD 73-23-07](https://openairdocs.org/ad/73-23-07): Defective Spar Attachment Fittings · Cessna 150, 150A, 150B and 68 more. Effective Nov 19, 1973
- [AD 73-17-01](https://openairdocs.org/ad/73-17-01): Fuel Transfer Pump Placard · Cessna 170, 170A, 170B and 53 more. Effective Aug 16, 1973
- [AD 71-22-02](https://openairdocs.org/ad/71-22-02): Cracks In Nose Gear Fork · Cessna 150, 150A, 150B and 52 more. Effective Nov 9, 1971
- [AD 71-18-01](https://openairdocs.org/ad/71-18-01): Fuel Selector Valve Placard · Cessna 172, 172A, 172B and 16 more. Effective Aug 31, 1971
- [AD 69-15-03](https://openairdocs.org/ad/69-15-03): Muffler Assembly · Lycoming O-320-A1A, A1B, A3A, A3B or Lycoming O-320-B1A, B1B… (D'Shannon Products STC SA135CE or 8 others). Effective Aug 20, 1969
- [AD 68-17-04](https://openairdocs.org/ad/68-17-04): Stall Warning System · Cessna 150, 150A, 150B and 63 more. Effective Sep 7, 1968

### Matched by engine (Porsche PFM3200N03)

- [AD 99-04-15](https://openairdocs.org/ad/99-04-15): Porsche K.-G., Dr. Ing.h.c.F. PFM3200N01, PFM3200N02 and PFM3200N03. Effective Apr 12, 1999

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

- [AD 87-20-03 R2](https://openairdocs.org/ad/87-20-03-R2) (historical): Seat Tracks · Cessna 150A, 150B, 150C and 212 more. Effective Sep 24, 1990
- [AD 80-04-08](https://openairdocs.org/ad/80-04-08) (historical): Fuel Lines · Cessna 172N, R172K, F172N and 1 more. Effective Feb 16, 1980

## Information bulletins (advisory) (11 in force)

- [SAIB AIR-21-16](https://openairdocs.org/saib/AIR-21-16): FLIGHT COMPARTMENT EQUIPMENT, Cessna Seat Back Attachment Bolt Inspection. Issued Aug 26, 2021
- [SAIB SW-18-31](https://openairdocs.org/saib/SW-18-31): NAVIGATION, ATTITUDE, AND DIRECTION DATA SYSTEM. Issued Nov 21, 2018
- [SAIB CE-18-23](https://openairdocs.org/saib/CE-18-23): Passenger Compartment Equipment - Installation of F. Atlee Dodge Aircraft Services LLC. Folding Jump Seats. Issued Jul 19, 2018
- [SAIB CE-17-25](https://openairdocs.org/saib/CE-17-25): ELEVATOR TORQUE TUBE  Inspections for cracks and corrosion in elevator torque tubes. Issued Aug 25, 2017
- [SAIB CE-12-14](https://openairdocs.org/saib/CE-12-14): Three Alternative Methods of Compliance for AD 2011-10-09. Issued Jan 25, 2012
- [SAIB CE-10-40R1](https://openairdocs.org/saib/CE-10-40R1): Aircraft Fuel System; water contamination of fuel tank systems on Cessna single engine airplanes. Issued Jul 30, 2010
- [SAIB CE-09-42](https://openairdocs.org/saib/CE-09-42): Lights - Landing Light, Beacon Light and Taxi Light Switch Applications. Issued Jul 24, 2009
- [SAIB CE-09-10](https://openairdocs.org/saib/CE-09-10): Availability of Secondary Seat Stops for Pilot and Copilot Seats. Issued Feb 5, 2009
- [SAIB CE-09-01](https://openairdocs.org/saib/CE-09-01): Equipment - Emergency. Issued Oct 21, 2008
- [SAIB CE-01-41R2](https://openairdocs.org/saib/CE-01-41R2): Flight Controls. Issued Oct 1, 2007
- [SAIB NE-09-21](https://openairdocs.org/saib/NE-09-21): Reciprocating Engine. Issued Mar 31, 2009
- [SAIB CE-10-40](https://openairdocs.org/saib/CE-10-40) (historical): Aircraft Fuel System; water contamination of fuel tank systems on Cessna single engine airplanes. Issued Jul 27, 2010
- [SAIB CE-01-41R1](https://openairdocs.org/saib/CE-01-41R1) (historical): Cracks in plastic or non-metallic control wheels. Issued Jan 10, 2007

## 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 ERA09CA058](https://openairdocs.org/ntsb/ERA09CA058), Nov 10, 2008: Cessna 172 (N172PA), Gulf Shores, AL, substantial damage. Probable cause: The pilot's improper flare during landing.

## FAA accident and incident reports (1)

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 20081110856609A](https://openairdocs.org/incident/20081110856609A), Nov 10, 2008: Cessna 172N (N172PA), Gulf Shores, AL, Substantial damage. (-23) On November 10, 2008, at approximately 15:00 CST, while flying as pilot in command, [privacy data omitted], private pilot certificate number [privacy…

## 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) (517, 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 172N)

- [STC SA01233SE](https://openairdocs.org/stc/SA01233SE): Fabrication and installation of Alaskan Bushwheel LLC tail wheel and fork assembly. ABI, LLC
- [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 SA02069AK](https://openairdocs.org/stc/SA02069AK): Fabrication and installation of the Airglas, Inc., Landes PA32-206LA Nose Fork equipped with up to a 8.50 x 6 tire. Airglas 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 SA01134DE](https://openairdocs.org/stc/SA01134DE): Installation of EarthX ETX680-24-TSO Lithium Battery. EarthX Inc
- [STC SA12406WI](https://openairdocs.org/stc/SA12406WI): Installation of a Garmin AXIS Flight Display System. Garmin International Inc
- [STC SA04652CH](https://openairdocs.org/stc/SA04652CH): To allow use of 100R grade aviation fuel meeting Swift Fuel, LLC specification. Swift Fuels LLC
- [STC SA02636SE](https://openairdocs.org/stc/SA02636SE): Installation of Garmin GPS 175 Navigation System and GNX 375 Navigation System with ADS-B In/Out Transponder. Garmin International Inc
- [STC SA03932NY](https://openairdocs.org/stc/SA03932NY): Installation and maintenance of XCAM Pod on port or starboard wing strut. J&C Engineering Services LTD
- [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 SA2714CE](https://openairdocs.org/stc/SA2714CE): Installation of Lycoming O-320-D2G or -D2J engine and McCauley1C160/DTM or Sensenich 74 DMS14-0 propeller. Air Plains Services Corporation
- [STC SA800EA](https://openairdocs.org/stc/SA800EA): Installation of Whelen Anti-Collision, Position, or Anti-Collision/Position Light System, and applicable associated power supplies. Whelen Aerospace Technologies
- [STC SA02511SE](https://openairdocs.org/stc/SA02511SE): Installation of replacement fuel quantity indicator sending unit(s). CiES Inc
- [STC SA01866WI](https://openairdocs.org/stc/SA01866WI): Installation of Garmin GFC 500 Autopilot with Electronic Stability and Protection. Garmin International Inc
- [STC SA12276IB](https://openairdocs.org/stc/SA12276IB): Payload System Installation. Icarus Aero Inc
- [STC SA04075CH](https://openairdocs.org/stc/SA04075CH): Installation of Dynon EFIS-D10A EAA sales kit part number 102778-000. Dynon Avionics Inc
- [STC SA02595AK](https://openairdocs.org/stc/SA02595AK): Fabrication and installation of Airglas Inc. cargo pod kit model LC172. Airglas Inc
- [STC SA01005DE](https://openairdocs.org/stc/SA01005DE): Installation of a EarthX ETX900-TSO Lithium battery. EarthX Inc
- [STC SA00081NY](https://openairdocs.org/stc/SA00081NY): Installation of Iceman Aviation Supplies, Inc. Carburetor Ice Detector. Alcor LLC
- [STC SA5581SW](https://openairdocs.org/stc/SA5581SW): Installation of ALCOR true-flow/ totalizer system. Alcor LLC. Lists 172 Series
- [STC SA01801AT](https://openairdocs.org/stc/SA01801AT): For the Cessna 172 airplane models incorporating Lycoming O-320 engines: Modification of the standard exhaust system as documented in Laminar Flow Systems Installation Instructions Document, "Laminar Flow System Extractor Exhaust System" Revision A, dated, November 20, 1998 and Technical Drawing List, Book No. PFS-B-800, dated, November 16, 1998 or per Power Flow Systems, Inc. Installation Instructions Document PFS-0058-00, Rev. A, dated October 5, 2001 and Master Drawing List, Report No. PFS-0032-00, Rev. IR, dated August 10, 2000, or later FAA approved revisions. For the Cessna 172 airplane models incorporating Lycoming O-320 ,O-360 0r IO-360 engines: Modify the standard exhaust system as document in Power Flow Systems, Inc. Installation Instructions Document PFS-13250-00, Rev B, dated, December 9, 2002 and Master Drawing list PFS-13240-00, Rev, IR, dated October 3, 2002. Power Flow Systems Inc
- [STC SA02228AT](https://openairdocs.org/stc/SA02228AT): For model 172 airplanes with Lycoming O-360 engines per STC SA332GL or STC SA4428SW, modification of standard exhaust system. For model 172 with Lycoming O-360 engines per STC SA647CE or STC SA1324CE, modification of standard exhaust system. Power Flow Systems Inc
- [STC SA1945CE](https://openairdocs.org/stc/SA1945CE): Increase normal category maximum gross weight from 2300 to 2400 lbs. and increase utility category maximum grow weight from 2000 to 2100 lbs. per Installation Instructions, STC SA1945CE, Gross Weight Increase for the C172N with an FAA approval date of January 3, 1989, or later. Power Flow Systems Inc
- [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 SA02588AK](https://openairdocs.org/stc/SA02588AK): Installation of Ground Adjustable Sensenich Composite 2G0M8S14/C76PGF Propeller. Sensenich Propeller Company
- [STC SA00037WI](https://openairdocs.org/stc/SA00037WI): Installation of B & C Specialty Products BC100-1 battery. B & C Specialty Products Inc
- [STC SA01330LA](https://openairdocs.org/stc/SA01330LA): Installation of alternate avionics support assembly. Radiorax Aviation Systems LLC
- [STC SA04378CH](https://openairdocs.org/stc/SA04378CH): Installation of an engine modified per STC SE04349CH. SureFly Partners Ltd
- [STC SA01120SE](https://openairdocs.org/stc/SA01120SE): Installation of Door Steward. Mountain View Aviation LLC
- [STC SA860SO](https://openairdocs.org/stc/SA860SO): Installation of portable hand control. Union Aviation LLC
- [STC SA39CH](https://openairdocs.org/stc/SA39CH): Installation of an Amphibian Landing Gear Position Advisory System/Laser Gear Advisory System. Wipaire Inc
- [STC SA02594SE](https://openairdocs.org/stc/SA02594SE): SkyView HDX Instrumentation and Autopilot System manufactured. Dynon Avionics
- [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 SA00622DE](https://openairdocs.org/stc/SA00622DE): Installation of John Deere AGRI Services, Inc. JD3 Aerial Imaging System,. Aeroptic LLC
- [STC SA04568CH](https://openairdocs.org/stc/SA04568CH): Installation of the uAvionix tailBeaconX, a tail mounted position light with integrated Automatic Dependent Surveillance - Broadcast (ADS-B) Out and 1090MHz Mode-S transponder functionality. uAvionix Corporation
- [STC SA02006CH](https://openairdocs.org/stc/SA02006CH): Installation of air conditioning system. Kelly Aerospace Thermal Systems LLC
- [STC SA00871SE](https://openairdocs.org/stc/SA00871SE): Installation of cockpit sunvisors. Rosen Sunvisor Systems 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 SA1168SO](https://openairdocs.org/stc/SA1168SO): Installation of Aqua Model 2200 floats. Outpost X Aviation Inc
- [STC SA665CE](https://openairdocs.org/stc/SA665CE): Installation of Model 2400 Aqua floats. (175 FLOATPLANE CONFIGURATION). Outpost X Aviation Inc
- [STC SA01899WI](https://openairdocs.org/stc/SA01899WI): Installation of Garmin G3X Touch Electronic Flight Instrument System. Garmin International Inc
- [STC SA826NE](https://openairdocs.org/stc/SA826NE): Installation of a 74DM7S14 fixed-pitch metal propeller. Sensenich Propeller Company
- [STC SA02575AK](https://openairdocs.org/stc/SA02575AK): Installation of the nose tire scraper P/N TSL-100. Aero Twin Inc
- [STC SA02576AK](https://openairdocs.org/stc/SA02576AK): Installation of Cleveland and ABI, LLC Wheel and Brake Kits. ABI LLC
- [STC SA02019WI](https://openairdocs.org/stc/SA02019WI): Installation of the Trig Avionics TX56, TX56A, TX57, or TX57A VHF Nav-Com Radio. Peregrine
- [STC SA04400NY](https://openairdocs.org/stc/SA04400NY): Installation of the Integrated Back-up Battery System (IBBS). TCW Technologies LLC

All 517: https://openairdocs.org/aircraft/N172PA/stcs.md

## Related

- Other Cessna 172N aircraft: https://openairdocs.org/model/cessna-172n/aircraft.md
- The Porsche PFM3200N03 engine: https://openairdocs.org/engine/porsche-pfm3200n03.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.
