# Service difficulty reports: Lycoming O-540-E4C5

A list on [Lycoming O-540-E4C5](https://openairdocs.org/engine/lycoming-o-540-e4c5.md).

Newest first. General aviation reporting is voluntary.

Page 1 of 3 · 139 reports

- [SDR 2026F00125](https://openairdocs.org/sdr/2026F00125.md): Rudder · no discrepancy · Jun 16, 2026 · N908VL · Bnorm BN2B26 · Rudder Control System
  > THE PILOT DEPARTED RWY 9 ON THE SUNNY TRANSITION TO VQS AND AT APPROXIMATELY 1 MILE NORTH OF PUNTA LAS MARIAS, THE PIC DECIDED TO RETURN TO SIG DUE TO STIFFNESS OF THE RIGHT RUDDER PEDDLE. AN EMERGENCY WAS NOT DECLARED DUE TO THE PIC HAVING FULL CONTROL OF TH
- [SDR 2025F00229](https://openairdocs.org/sdr/2025F00229.md): Engine · failed · Aug 15, 2025 · Bnorm BN2A · Engine (Reciprocating)
  > FLT NUMBER: DVR023, ENGINE FAILURE AND EMERGENCY LANDING. SHORTLY AFTER DEPARTURE FROM BON, THE CREW EXPERIENCED A LOSS OF FUEL PRESSURE AND OBSERVED A DECREASING OIL PRESSURE ON THE LEFT-HAND (LH) ENGINE. DUE TO THESE CRITICAL INDICATIONS, A PRECAUTIONARY SH
- [SDR UOIA202507020001](https://openairdocs.org/sdr/UOIA202507020001.md): Idler Gear · damaged · Jul 2, 2025 · N904GD · Bnorm BN2B26 · Engine (Reciprocating)
  > PILOT REPORTED THAT DURING CRUISE FLIGHT FROM TJIG TO TJCP LEFT ENGINE OIL PRESSURE STARTED DROPPING AND AFTER A FEW SECONDS PROPELLER FETHERED BY ITSELF AND ENGINE SHUT DOWN. PILOT PERFORMED ENGINE FAILURE PROCEDURE AS PER FLIGHT MANUAL AND DIVERTED TO TJRV A
- [SDR UOIA202506300001](https://openairdocs.org/sdr/UOIA202506300001.md): Spark Plug · faulted · Jun 30, 2025 · N903GD · Bnorm BN2A8 · Spark Plug/Igniter
  > DURING CLIMB PILOT NOTICED LEFT ENGINE SOUNDED ROUGH AND DECIDED TO RETUN TO THE AIRPORT AS PRECAUTION. UPON EXAMINATION MAINTENANCE PERFORMED LEFT ENGINE COLD CHECK AND REPLACED CYLINDERS #1, #3, AND #5 TOP SPARK PLUGS AS PER LYCOMING OH MANUAL CHAPTER 4. P
- [SDR 2025F00108](https://openairdocs.org/sdr/2025F00108.md): Shaft · broken · Apr 25, 2025 · N903GD · Bnorm BN2A8 · Propeller Governor
  > AT LANDING IN VIEQUES AIRPORT RIGHT ENGINE PRESENTED EXESIVE VIBRATION, PILOT PERFORMED PREVENTIVE SHUTDOWN. ENGINE WAS INSPECTED AND FOUND THE PROPELLER GOVERNOR SHAFT BROKEN. PROPELLER GOVERNOR WAS REMOVED AND OVERHAULED PROPELLER GOVERNOR INSTALLED. OPERATI
- [SDR UOIA2025042500006](https://openairdocs.org/sdr/UOIA2025042500006.md): Shaft · broken · Apr 25, 2025 · N903GD · Bnorm BN2A8 · Propeller Governor
  > AT LANDING IN VIEQUES AIRPORT RIGHT ENGINE PRESENTED EXCESSIVE VIBRATION SO PILOT PERFORMED PREVENTIVE SHUTDOWN. ENGINE WAS INSPECTED AND FOUND THE PROPELLER GOVERNOR SHAFT BROKEN. PROPELLER GOVERNOR WAS REMOVED AND AN OVERHAULED PROPELLER GOVERNOR INSTALLED.
- [SDR VLIA202406250001](https://openairdocs.org/sdr/VLIA202406250001.md): Brake Disc · cracked · Jun 21, 2024 · N864VL · Bnorm BN2A9 · Landing Gear Brake System
  > DURING THE LANDING ROLL WHEN BRAKES WHERE APPLIED THE R/H BRAKE BEGIN TO DRAG. UPON INSPECTION FOUND THE R/H LANDING GEAR OUTBOARD WHEEL DISC CRACK.
- [SDR UOIA2023041200006](https://openairdocs.org/sdr/UOIA2023041200006.md): Master Cylinder · blocked · Apr 12, 2023 · N903GD · Bnorm BN2A8 · Master Cylinder/Brake Valve
  > AFTER LANDING LOSS BRAKE ACTION.
- [SDR UOIA2023012800005](https://openairdocs.org/sdr/UOIA2023012800005.md): Crankshaft · broken · Jan 28, 2023 · N907GD · Bnorm BN2A26 · Engine (Reciprocating)
  > AFTER LANDING IN CULEBRA, RIGHT ENGINE QUIT ON TAXI TO THE RAMP. ENGINE WAS INSPECTED AND THE ENGINE CRANKSHAFT IDLE GEAR FOUND BROKEN. ENGINE WAS REMOVED AND REPLACED.
- [SDR UOIA2022112200004](https://openairdocs.org/sdr/UOIA2022112200004.md): Control Cable · lack of lube · Nov 22, 2022 · N904GD · Bnorm BN2B26 · Propeller Controlling System
  > LEFT PROPELLER GETTING STUCK INTERMITTENT.
- [SDR 2022F00331](https://openairdocs.org/sdr/2022F00331.md): None · none · Aug 29, 2022 · N905GD · Bnorm BN2 · Engine (Reciprocating)
  > LEFT ENGINE SURGING PRECAUTIONARY SHUT DOWN.
- [SDR 2021F00092](https://openairdocs.org/sdr/2021F00092.md): Gear · broken · Apr 28, 2021 · N404WB · Bnorm BN2A26 · Magneto/Distributor
  > PILOT PERFORMED PRE FLIGHT MAGNETO CHECK. THE LH MAG WAS INOPERATIVE. FURTHER INSPECTION BY MX PERSONNEL DISCOVERED THE LH MAGNETO DRIVE GEAR WAS MISSING 3 TEETH; MAKING THE MAGNETO NOT FUNCTIONAL.
- [SDR UOIA2020111300002](https://openairdocs.org/sdr/UOIA2020111300002.md): Governor · damaged · Nov 12, 2020 · N920GD · Bnorm BN2AMK3 · Engine Pressure Ratio (EPR)
  > LOSS OF RPM ON TAKEOFF.
- [SDR UOIA2020071400001](https://openairdocs.org/sdr/UOIA2020071400001.md): Cylinder · damaged · Jul 14, 2020 · N913GD · Bnorm BN2A8 · Reciprocating Engine Cylinder Section
  > ENGINE LOST POWER.
- [SDR UOIA2019009130000](https://openairdocs.org/sdr/UOIA2019009130000.md): Crankshaft · failed · Sep 7, 2019 · N917GD · Bnorm BN2A27 · Reciprocating Engine Power Section
  > ENGINE CRANKSHAFT GEAR FAILURE.
- [SDR UOIA2017080300001](https://openairdocs.org/sdr/UOIA2017080300001.md): Caliper · broken · Aug 3, 2017 · N906GD · Bnorm BN2A26 · Landing Gear Brake System
  > RIGHT BRAKE FAILED TO OPERATED, THE AIRCRAFT GO OUT OF RUNWAY.
- [SDR UOIA201703070001](https://openairdocs.org/sdr/UOIA201703070001.md): Shaft · broken · Jul 3, 2017 · N917GD · Bnorm BN2A27 · Propeller Governor
  > RIGHT PROPELLER GOES TO FEATHER CONDITION. PROPELLER GOVERNOR SHAFT BROKEN.
- [SDR UOIA20170803](https://openairdocs.org/sdr/UOIA20170803.md): Rudder · inoperative · Mar 8, 2017 · N906GD · Bnorm BN2A26 · Rudder Control System
  > DURING FLIGHT RUDDERS STOPPED RESPONDING.
- [SDR UOIA201606131114](https://openairdocs.org/sdr/UOIA201606131114.md): Caliper · leaking · Jun 10, 2016 · N906GD · Bnorm BN2A · Landing Gear Brake System
  > LOST RT BRAKES EMERGING THE RUNWAY FOR TAKEOFF. R & R RT MAIN INBD CALIPER AND LINING.
- [SDR UOIA201510071114](https://openairdocs.org/sdr/UOIA201510071114.md): Stud · broken · Oct 6, 2015 · N906GD · Bnorm BN2A26 · Reciprocating Engine Power Section
  > LEFT ENG CYLINDER NR 3 CRANKCASE STUDS BROKEN.
- [SDR RI9A20150809001](https://openairdocs.org/sdr/RI9A20150809001.md): Starter · binding · Aug 3, 2015 · N5891V · Bnorm BN2A26 · Engine Starter
  > BENDIX ON STARTER OF RT ENGINE FAILED TO DISENGAGE AFTER STARTUP. R & R STARTER WITH NEW. NO FURTHER DISCREPANCIES NOTED.
- [SDR LU4R2015020618118](https://openairdocs.org/sdr/LU4R2015020618118.md): Blade · cracked · Feb 3, 2015 · N908GD · Bnorm BN2A26 · Propeller Blade Section
  > PROPELLER BLADE FOUND CRACKED AT SHANK.
- [SDR WS9R2015FA0000008](https://openairdocs.org/sdr/WS9R2015FA0000008.md): Crankshaft · broken · Dec 22, 2014 · N5891V · Bnorm BN2A26 · Reciprocating Engine Power Section
  > ENGINE RECEIVED FOR O/H DUE TO HIGH METAL. DURING DISASSEMBLY, IT WAS DISCOVERED THAT A PIECE OF THE CHEEK ON THE CRANKSHAFT HAD BROKEN OFF ALLOWING THE COUNTERWEIGHT TO IMPACT CONNECTING RODS AND THE CRANKSHAFT. THE COUNTERWEIGHT PINS WERE UNDAMAGED. THE C
- [SDR UOIA20141114001](https://openairdocs.org/sdr/UOIA20141114001.md): Stud · broken · Nov 12, 2014 · N901GD · Bnorm BN2A · Reciprocating Engine Power Section
  > RIGHT ENG CYLINDER BASE NR 3 STUDS BROKEN.
- [SDR UOIA2014FA0000525](https://openairdocs.org/sdr/UOIA2014FA0000525.md): Cylinder · cracked · Sep 9, 2014 · N908GD · Bnorm BN2A · Reciprocating Engine Cylinder Section
  > LEFT ENGINE, CYLINDER 2, CENTER AREA CRACKED.
- [SDR CA140506002](https://openairdocs.org/sdr/CA140506002.md): Adapter · cracked · May 5, 2014 · Reciprocating Engine Oil System
  > (CAN) AIRCRAFT IS AN AMATEUR BUILT, ENGINE AND SUBJECT OIL FILTER ADAPTER ARE USED ON MANY CERTIFIED ACFT. DURING ANNUAL INSPECTION SUBSTANTIAL OIL LEAK WAS NOTED ON BACK OF ENGINE. TROUBLESHOOTING SOURCED OIL LEAK TO CRACK ON OIL FILTER ADAPTER EAR. CRACK C
- [SDR CA140204009](https://openairdocs.org/sdr/CA140204009.md): Spring · broken · Jan 20, 2014 · Bnorm BN2B27 · Reciprocating Engine Cylinder Section
  > (CAN) DURING 100HR INSPECTION, FOUND SPRING BROKEN ON INTAKE VALVE LT ENGINE.
- [SDR ISCA2014F00011](https://openairdocs.org/sdr/ISCA2014F00011.md): Case · damaged · Oct 4, 2013 · N779KS · Bnorm BN2A27 · Reciprocating Engine Power Section
  > PILOT REPORTED THAT ON DOWNWIND IN THE TRAFFIC PATTERN AT THE DESTINATION AIRPORT, HEARD A LOUD "POP", AND AND EXPERIENCED A POWER LOSS ON LT ENGINE. NOTICED OIL AND SMOKE COMING OUT OF LT ENGINE COWL. SHUTDOWN ENGINE AND FEATHERED PROPELLER IAW THE ENGINE
- [SDR ISCA2013111400001](https://openairdocs.org/sdr/ISCA2013111400001.md): Retainer · disintegrated · Oct 4, 2013 · N779KS · Bnorm BN2B27 · Reciprocating Engine Power Section
  > PILOT REPORTED THAT ON DOWNWIND, IN TRAFFIC PATTERN AT DESTINATION AIRPORT, HEARD A LOUD "POP," AND EXPERIENCED A POWER LOSS ON THE LT ENGINE. ALSO NOTICED OIL AND SMOKE COMING OUT OF LT ENGINE COWL. SHUTDOWN ENGINE AND FEATHERED PROPELLER IAW ENGINE FAILUR
- [SDR 2013FA0000584](https://openairdocs.org/sdr/2013FA0000584.md): Case · cracked · Oct 1, 2013 · N80KM · Bnorm BN2A · Reciprocating Engine Power Section
  > WHILE TROUBLESHOOTING ROUGH RUNNING ENGINE ON MORNING RUNUP, ENGINE CASE FOUND WITH LARGE CRACK UNDER THE NR 2 CYLINDER, ENGINE REMOVED FROM SERVICE.
- [SDR CA130516009](https://openairdocs.org/sdr/CA130516009.md): Rod End · loose · May 1, 2013 · Bnorm BN2A8 · Flight Control System
  > (CAN) ROD END BEARING NOTED TO BE MOVING DUE TO LOOSE TAPER PINS IN FWD END OF RUDDER DRIVE ROD. ROD REPAIRED AND RE-INSTALLED.
- [SDR RI9A20120807557](https://openairdocs.org/sdr/RI9A20120807557.md): Crankcase · cracked · Aug 5, 2012 · N5891V · Bnorm BN2A26 · Reciprocating Engine Power Section
  > PILOT HEARD RIGHT ENGINE RUNNING ROUGH AND SAW THE OIL PRESSURE DROP. SHUT THE ENGINE DOWN AND MADE A SAFE LANDING AT OUZINKIE AIR STRIP. UPON INSPECTION FOUND A CRACK IN THE CRANKCASE BETWEEN THE NR 3 AND NR 5 CYLINDERS. A NEW ENGINE WAS INSTALLED. AFTER
- [SDR RI9A20120617001](https://openairdocs.org/sdr/RI9A20120617001.md): Regulator · malfunctioned · Jun 6, 2012 · N5891V · Bnorm BN2A26 · DC Regulator
  > PILOT SMELLED ODOR AND SAW SMOKE FROM INSTRUMENT PANEL. PILOT RETURNED TO KODIAK AIRPORT WITHOUT INCIDENT AND MADE A NORMAL LANDING. ON INVESTIGATION, IT WAS FOUND THE RIGHT ENGINE ALTERNATOR VOLTAGE REGULATOR HAD CAUSED AN OVERVOLTAGE SITUATION AND THE SMOK
- [SDR RI9A2012FA0000125](https://openairdocs.org/sdr/RI9A2012FA0000125.md): Case · damaged · Feb 20, 2012 · N2233Z · Bnorm BN2A26 · Reciprocating Engine Power Section
  > PILOT EXPERIENCED AN ROUGH RUNNING LT ENGINE 20 MINUTES INTO THE FLIGHT. THE PILOT REPORTED THAT ALL LT ENGINE INSTRUMENT INDICATIONS WERE NORMAL AT THAT TIME. OIL PRESSURE DROPPED TO ZERO, TURNED BACK TO AIRPORT. DECLARED AN EMERGENCY AND LANDED WITHOUT AN
- [SDR CA111207006](https://openairdocs.org/sdr/CA111207006.md): Alternator · failed · Nov 27, 2011 · Bnorm BN2A27 · AC Generator-Alternator
  > (CAN) NOTED ALTERNATOR OUT LIGHT DURING RUNUP. LT ALTERNATOR WAS FOUND SEIZED AND DISCOLORED BY HIGH TEMPERATURE. ALTERNATOR BELT WAS ALSO FOUND BROKEN. ALTERNATOR TT WAS 119.5 SINCE O/H. ALTERNATOR WAS REPLACED WITH SERVICEABLE SPARE AND RETURNED TO SERVI
- [SDR UOI2011F00001](https://openairdocs.org/sdr/UOI2011F00001.md): Bolt · broken · Apr 7, 2011 · N904GD · Bnorm BN2B26 · Engine (Reciprocating)
  > BOLT DAMAGE, IDLER GEAR SHAFT BOLT.
- [SDR ISCA2011022201](https://openairdocs.org/sdr/ISCA2011022201.md): Retaining Nut · failed · Feb 18, 2011 · N779KS · Bnorm BN2A26 · Reciprocating Engine Cylinder Section
  > IN CRUISE FLT, AT 2500 FT AGL & APPROX 15 MILES FROM DESTINATION, PILOT NOTED A SLIGHT VIBRATION ON STARBOARD (RT) ENG FOLLOWED BY A LOUD BANG. IN RESPONSE, PILOT SHUT THE ENG DOWN, AND FEATHERED PROP. AFTER LANDING, THE POST-FLIGHT INSP REVEALED THE NR 3 CY
- [SDR UOI2011F00000](https://openairdocs.org/sdr/UOI2011F00000.md): Drive Assy · worn · Dec 31, 2010 · N908GD · Bnorm BN2A26 · Propeller Governor
  > (ENGINE INTERNAL) PROPELLER GOVERNOR DRIVE DAMAGE.
- [SDR CA100723007](https://openairdocs.org/sdr/CA100723007.md): Impulse Coupling · broken · Jul 23, 2010 · Bnorm BN2A26 · Magneto/Distributor
  > MAG WAS RECEIVED DUE TO SEIZED CONDITION. UNKNOWN WHEN IT OCCURRED DURING ENG OPERATION. 1 IMPULSE FLYWEIGHT WAS FOUND BROKEN AWAY FROM IMPULSE ASSY AND WEDGED BETWEEN THE OTHER FLYWEIGHT AND THE MAG HOUSING. THE IMPULSE COUPLING WAS REMOVED AND THE RIVET TH
- [SDR CA090119013](https://openairdocs.org/sdr/CA090119013.md): Sleeve · loose · Jan 18, 2009 · Bnorm BN2A26 · Engine Air Intake System
  > ON GROUND RUN IT WAS DISCOVERED THAT CYLINDER NR 5 ON THE RIGHT ENGINE, EGT WAS NOTICABLY HIGHER THAN OTHER CYLINDERS. INDUCTION TUBE WAS REMOVED FROM THE CYLINDER, THE INDUCTION TUBE SLEEVE IN THE OIL SUMP WAS FOUND TO BE LOOSE.
- [SDR CA081015002](https://openairdocs.org/sdr/CA081015002.md): Spring · broken · Oct 6, 2008 · Bnorm BN2B27 · Reciprocating Engine Cylinder Section
  > (CAN) DURING INSPECTION OF LYCOMING SB 388C FOUND BROKEN INNER SPRING PART NR AEL11795 ON INTAKE AND EXHAUST VALVE.
- [SDR G0C2008F00000](https://openairdocs.org/sdr/G0C2008F00000.md): Cylinder Head · separated · Jul 3, 2008 · N2119V · Bnorm BN2B26 · Reciprocating Engine Cylinder Section
  > NR 5 CYLINDER FAILED DUE TO CYLINDER HEAD SEPARATION FROM BARREL. AC IMMEDIATELY DIVERTED TO NEAREST AIRFIELD FOR REPAIR. AC LANDED SAFELY, POWER SETTING AT FAILURE WAS 25 IN MAN PRESSURE, 2200 RPM. AC WAS IN CRUISE SEGMENT. ENG WAS IN COMPLIANCE WITH ALL
- [SDR CA080608003](https://openairdocs.org/sdr/CA080608003.md): Nut · stripped · Jun 3, 2008 · Bnorm BN2A26 · Trailing Edge Flap Actuator
  > (CAN) DURING A TRAINING FLIGHT, ON OVERSHOOT FROM A ABORTED LANDING, FLAPS RETRACTED UN-COMMANDED. PILOT REDUCED POWER AND WAS ABLE TO LAND STRAIGHT AHEAD ON REMAINING RUNWAY. INSPECTION FOUND THE FLAP ACTUATOR STRIPED. ACTUATOR WAS REMOVED AND SENT FOR OVERH
- [SDR FFKA020108125](https://openairdocs.org/sdr/FFKA020108125.md): Drive Shaft · sheared · Feb 1, 2008 · N4817S · Piper PA32260 · Engine (Reciprocating)
  > PILOT REPORTED A LOSS OF ENGINE RPM CONTROL (RUNAWAY PROP). AFTER REPLACING THE PROPELLER GOVERNOR AND THE PROPELLER THERE WAS STILL NO PROP CONTROL. MAINTENANCE FURTHER INVESTIGATED THE PROBLEM AND FOUND THE PROPELLER GOVERNOR DRIVE SHAFT GEAR SHEARED. AFT
- [SDR CA070202008](https://openairdocs.org/sdr/CA070202008.md): Collar · broken · Jan 30, 2007 · Bnorm BN2A26 · Steering Unit
  > (CAN) NOSE LANDING GEAR STEERING COLLAR, BROKE IN TWO PIECES DURING GROUND HANDLING. COLLAR CRACKED AFT GREASE FITTING HOLE ANF FWD RT RELEASE DOG SLOT. (TC NR 20070202008)
- [SDR 2006F00037](https://openairdocs.org/sdr/2006F00037.md): Bearing · worn · Aug 31, 2006 · N131JL · Bnorm BN2A · Magneto/Distributor
  > ON SCHEDULED INSPECTION FOUND VERY SMALL METAL PARTICLES IN OIL FILTER, NONE FOUND IN FINGER SCREEN. REMOVED ENGINE AND SEND FOR INSPECTION AND REPAIR. AFTER COMPLETION OF ENGINE TEAR DOWN EVERYTHING WAS WITHIN SPECS BUT THE LT MAGNETO DRIVE GEAR BEARING WOR
- [SDR CA070126004](https://openairdocs.org/sdr/CA070126004.md): Oil Cooler · cracked · Aug 31, 2006 · Bnorm BN2A · Engine Oil Cooler
  > (CAN) OIL LEAK AROUND CASTING PORT ON THE OIL COOLER ASSEMBLY. (TC NR 20070126004)
- [SDR CA070126003](https://openairdocs.org/sdr/CA070126003.md): Magneto · loose · Jul 5, 2006 · Bnorm BN2A · Magneto/Distributor
  > (CAN) ROUGH RUNNING ON RUNUP. FOUND ATTACHMENT FLANGE ON MAGNETO LOOSE. (TC NR 20070126003)
- [SDR CA060702001](https://openairdocs.org/sdr/CA060702001.md): Wheel · cracked · Jun 13, 2006 · Bnorm BN2A26 · Wheel/Ski/Float
  > (CAN) ON TAXI AFTER LDG, A VIBRATION WAS NOTED ORIGINATION ON THE LH LDG GEAR. IT WAS ORIGINALLY THOUGHT TO BE A WHEEL OUT OF BALANCE. ON INSPECTION, A CRACK WAS OBSERVED ON THE INNER WHEEL 1/2 OUTBOARD ASSEMBLY. THE CRACKED RIM WAS REPLACED WITH NEW CLEAVL
- [SDR AU510002180](https://openairdocs.org/sdr/AU510002180.md): Valve · mismanufactured · Dec 12, 2005 · Fuel Control/Reciprocating Engines
  > (AUS) CARBURRETOR MIXTURE VALVE FAULTY MANUFACTURE. INSPECTION FOUND THE BRASS VALVE END OF THE MIXTURE VALVE ASSEMBLY HAD NOT BEEN CORRECTLY SWAGED CAUSING THE BRASS END TO TURN ON THE CABLE. (CASA NR 510002180)

Next page: https://openairdocs.org/engine/lycoming-o-540-e4c5/reports.md?page=2

## The whole list in SQL

Runs in DuckDB 1.2 or later on the release's Parquet files over HTTPS:

```sql
SELECT sdr_id, difficulty_date, n_number, aircraft_make, aircraft_model, part_name, part_condition, jasc_code, discrepancy
FROM 'https://openairdocs.org/data/latest/faa_service_difficulty_report.parquet'
WHERE engine_model_key = 'O540E4C5'
ORDER BY difficulty_date DESC
```

This list as a web page: https://openairdocs.org/engine/lycoming-o-540-e4c5/reports

---
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.