Service difficulty reports

1,768,504 reports of malfunctions and defects, newest first. Air carriers must report; general aviation reporting is voluntary.

Query with SQL
duckdb -csv -c "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'
  ORDER BY difficulty_date DESC"

Prints the whole list as CSV. It reads the release’s Parquet files over HTTPS, so there’s nothing to download first. Install DuckDB to run it.

SDR AALA202610224104Flap System · fault messageAIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED INTO DFW DUE TO THE FLIGHT CREW REPORTING THAT DURING DESCENT WITH THE FLAP LEVER IN POSITION 1 AND UPON SELECTING FLAP POSITION 2 AN ECAM FOR FLIGHT CONTROL FLAPS LOCKED AND ALIGNMENT FAULT DISPLAYED - THE FLIGOct 18, 2026 · N172US · Airbus A321211 · Trailing Edge Flap Control SystemSDR CALA2026102220514Computer · faultedNORMAL TAKEOFF, AT 500FT LOST BOTH FLIGHT DIRECTORS, ATC GAVE CLIMB 28K ALTITUDE, WINDOW WENT TO 50K & ENTIRE MODE CONTROL PANEL FROZEN. HAD A LOUD ALTITUDE DEVIATION HORN GOING OFF COULDN`T SILENCE. CAPT HDG SELECTOR ON MFD WAS ABOUT 180 DEG DIFFERENT THAOct 18, 2026 · N27724 · Boeing 737724 · Autopilot ComputerSDR CALA2026102220512Battery · inoperativeAHM DETECTED WELS MSG 33-12130. REMOTE WELS CONTROL UNIT CONFIGURATION DOES NOT AGREE WITH OTHER WIRELESS EMERGENCY LIGHTING SYS CONTROL UNITS. REF FIM DMC-B787-A-33-50-F1-P2A-421A-A TO CONFIRM FAULT. REF CONFIG DWG 2500DD15922 TO AID LOCATING WCU CLASS 30.Oct 18, 2026 · N27958 · Boeing 7879 · Emergency LightingSDR DALA2026102105808Battery Pack · failedFIRST CLASS EMERGENCY LIGHTS INOPERATIVE AFTER ON FOR LESS THAN ONE MINUTE. REMOVED AND REPLACED BATTERY PACK M2816 IAW AMM 33-51. (9516811) AIRCRAFT WAS GROUNDEDOct 18, 2026 · N831DN · Boeing 737932ER · Emergency LightingSDR DALA2026102105805Elec Connector · damaged18D EMERGENCY LIGHT INOP. FOUND NO VDC DROP AT BOTH RED & WHITE 18D FLOOR PROX EMER LIGHT , REMOVED & REPLACED M1694 BAT PACK, CLEANED THE CONNECTOR D12010 AT THE EXIT OF THE PWR SUPLY, FOUD OPEN LINE BETWEEN D12010 AND BOTH LIGHT, UPON INSPECTION OF THE CONOct 18, 2026 · N394DA · Boeing 737832 · Light System WiringSDR IPXA2026102108780Floor Panel · damagedMAJOR REPAIR, FOUND MAIN DECK FLOOR PANEL DAMAGE. IAW AMM 25-57-02-004-029, AMM 25-57-05-004-001 AND AMM 25-58-04-004-010 REV.149 REMOVED MAIN DECK CARGO HANDLING AND G.V.I CHECK NORMAL.IAW AMM 53-01-06-000-801 REV.149, REMOVED MAIN DECK CARGO FLOOR PANEL. Oct 18, 2026 · N322UP · Boeing 76734AF · Fuselage Floor PanelSDR VNAA2026102126801Actuator · trippedFLAPS FAIL MSG DURING CRUISE, RAN QRH AND FLAPS DID NOT EXTEND PAST FLAPS 1 POSITION C/A REPLACED #4 FLAP ACTUATOR.Oct 18, 2026 · N547NN · Cndair CL6002D24 · Trailing Edge Flap ActuatorSDR IXXA20261018104Cover · inoperativeESCAPE SLIDE DISARM LEVER COVER WILL NOT STOW. PLACED ON DEFERRAL 78046 NON-ESSENTIAL FURNISHINGS PER ATI-25-20-01-01-N3029. DUE 16 FEBRUARY 2027.Oct 18, 2026 · N389AZ · Boeing 767319 · Emergency EquipmentSDR R61A2026102100309Slide · deployedL1 DOOR SLIDE DEPLOYED. MECHANIC REMOVED THE DEPLOYED L1 DOOR EMERGENCY EVACUATION SLIDE IAW AMM AND REPLACED L1 DOOR SLIDE IAW SRIIM INSPECTOR PERFORMED RII INSPECTION OF L1 EMERGENCY EVACUATION SLIDE REPLACEMENT IAW SRIIMOct 18, 2026 · N233JQ · Emb ERJ170200LR · Escape SlideSDR DALA2026102105781Panel · missingBELLY FAIRING SLIDING PANEL, LT BELLY FAIRING SLIDING PANEL MISSING. FWD TO CDL 57-00-02. "M" PROC C/W. DISPATCH APPROVED. CDL AND PLAC INSTALLED. (LP: 9191132, AIRCRAFT WAS GROUNDED)Oct 18, 2026 · N378NW · Airbus A320211 · Aerodynamic FairingsSDR DALA2026102105780Flap System · lockedFLT CTL FLAP SYS 2 LOCKED. FLT CTL FLAPS SYS 2 FAULT MESSAGE. FWD TO MEL SFCS 2 FLAP CHANNEL PER MEL 27-51-01A. DISPATCH APPROVED. PLACARD INSTALLED. BACKDATED TO 18OCT26SFCC #2 FLAP CHANNEL DE-ACTIVATED. TROUBLESHOT I.A.W A321 TSM 27-51. REMOVED AND REPLACEDOct 18, 2026 · N373NW · Airbus A320212 · Trailing Edge Flap Control SystemSDR CALA2026102120503Support · crackedLEFT MLG WW, FWD SEAL RETAINER, SUPPORT FRAME OTBD END CRACKED. REMOVED AND REPLACED THE SEAL RETAINER SUPPORT IAW SRM 51-40-02-OG-0. REMOVED AND REINSTALL FOR ACCESS FOR ACCESS PANEL 197BL AND PANEL IAW AMM 53-66-01-404-005.Oct 18, 2026 · N41135 · Boeing 757224 · Fuselage Miscellaneous StructureSDR CALA2026102120501Guide Arm · crackedINSPECT ALL MAIN CABIN ENTRY DOORS FOR GUIDE ARM SECURITY. PERFORMED INSPECTION ON ALL MAIN CABIN ENTRY DOORS (L1, R1,L2, L4, & R4) GUIDE ARMS BRACKET BOLTS IAW AMM 52-11-04-402- 037 AND AMM 20-11-00-912-001 T97605, T97654. WC: 20026.Oct 18, 2026 · N41135 · Boeing 757224 · Service DoorsSDR CALA2026102120499Autopilot Sys · malfunctionedBOTH CAPTAIN`S & FIRST OFFICER`S AUTOPILOT P/RST AMBER LIGHT ILLUMINATED INTERMITTENTLY THROUGHOUT THE FLIGHT. AUTOPILOT STAYED CONNECTED. ALSO APPEARED WITH THE AUTOPILOT DISCONNECTED. PERFORMED AUTOPILOT TEST, FAULT STAB POS SEN-2. COMPLIED WITH MEL 2201BOct 18, 2026 · N12216 · Boeing 737824 · Autopilot SystemSDR CALA2026102120484Battery Pack · inoperativeEMERGENCY LIGHTS DID NOT COME ON ROWS 22, 23, 24, 25 ABC. FOUND BATTERY PACK DEAD AT BS 500E, REPLACED THE BATTERY, SYSTEM CHKD GOOD.Oct 18, 2026 · N77430 · Boeing 737924ER · Emergency LightingSDR CALA2026102120480Oven · smokeOVEN 204 SMOKING DURING USE. DEACTIVATED VIA CIRCUIT BREAKER IN FWD GALLEY IAW AMM 05-51-58-910-801-C1, REV 140. DURING OPS OF THE OVEN & FOUND HEAVY CONTAMINATION WITH FOOD, FOOD REMOVED AND TESTED AGAIN, ODOR REMAINS, OVEN C/B TRIPPED. IAW AMM 25-34-00-4Oct 18, 2026 · N17105 · Boeing 757224 · Buffet/GalleysSDR 2026FA0000880Hydraulic Line · looseHYD G RSVR LO LVL DURING CLIMB. IAW AMM 29-11-49-400-049-A REV 78, THE GREEN HCE PIPE#6 NUT WAS TORQUED AND ADJUSTED PROPERLY SATISFACTORY. THE OPERATIONAL TEST OF THE GREEN HYD SYS WAS PERFORMED SATISFACTORY IAW AMM 12-12-24-611-002-A THE GREEN RSVR WAS SERVOct 18, 2026 · N955AV · Airbus A320214 · Hydraulic System, MainSDR DXTA2026102010283Precatch · out of adjustMAIN DOOR PRE-CATCH IS NOT AUTOMATICALLY RELEASING WHEN OPENING THE DOOR FROM EITHER INSIDE OR OUTSIDE. DOOR WILL OPEN BUT REQUIRES PRECATCH BUTTON TO BE PUSHED. ADJUSTED PRECATCH CABLE IAW AMM 52-10-01AND OPS CHECKED GOOD.Oct 18, 2026 · N14QS · Cessna 560XL · Emergency ExitsSDR AALA202610201502Bottle · low pressureAIRCRAFT WAS NOT GROUNDED: CIDS CAUTION LIGHT ON FRONT GALLEY PANEL - MAINTENANCE SERVICED L3 DOOR DAMPER AND EMERGENCY OPERATION CYLINDER PER AMM 52-22-00 WHICH CLEARED THE CIDS CAUTION LIGHTOct 18, 2026 · N182UW · Airbus A321211 · Passenger/Crew DoorsSDR AALA202610207881Bottle · low pressureAIRCRAFT WAS NOT GROUNDED: FLIGHT ATTENDANT REPORTS DOOR 1R PRESSURE MESSAGE ON FLIGHT ATTENDANTS DISPLAY PANEL - MAINTENANCE SERVICED THE R1 DOOR DAMPER AND EMERGENCY OPERATION CYLINDER PER AMM 52-10-00 WHICH CLEARED THE MESSAGE ON THE FLIGHT ATTENDANTS DISPLOct 18, 2026 · N157UW · Airbus A321211 · Door Warning SystemSDR MASA2026101800049Mau · faultedACFT RETURNED TO FIELD, DECLARED AN EMERGENCY AFTER TAKEOFF, WHEN MULTIPLE MESSAGES APPEARED. AT FAIL/FMS SPEED ON PFD WILL NOT SHOW. SECURED CONTROL I/O MODULE MAU1 SLOT 6 IAW AMM 31-41-05. OPS CHECKED GOOD. NO FURTHER DEFECTS NOTED.Oct 18, 2026 · N89304 · Emb ERJ170200LR · Central ComputersSDR WX0A2026101932978Unknown · odorDIRTY SOCK SMELL REPORTED BY FA'S DURING DESCENT BELOW FL 180 / PERFORMED ALLEGIANT TASK CARD A32X-21-000-001. UNABLE TO REPRODUCE SMELL. CREATED M313 FOR TASK CARD A32X-21-000-002."Oct 18, 2026 · N209NV · Airbus A320214 · Air Distribution SystemSDR SWIA2026101877761Warning Light · illuminatedGEAR DISAGREE ON GEAR RETRACTION, NOSE GEAR INDICATOR WENT RED, A GEAR DISAGREE AURORAL. AFTER 30 SECONDS MESSAGE EXTINGUISHED. RAN QRH & DID LOW APPROACH TO ENSURE GEAR WAS DOWN, LANDING UNEVENTFUL. FLIGHT 5416. OPENOct 18, 2026 · N779SK · Cndair CL6002C11 · Landing Gear Position and WarningSDR SWIA2026101877759None · noneSMELL OF SMOKE IN FWD CABIN, SMOKE ALARM WENT OFF IN FWD LAV FOR 60 SECONDS, RECEIVED SMOKE LAV WARNING MESSAGE. FLIGHT 6355. ON ARRIVAL, INSPECTED FWD LAV FOR ANY SIGNS OF BURNED WIRING, LIGHT BULBS OR ELECT ISSUES, NONE FOUND. OPERATED PACKS AND RAN BOTOct 18, 2026 · N246LR · Cndair CL6002D24 · Standard Practices/StructuresSDR AALA202610192131Stop · brokenAIRCRAFT WAS NOT GROUNDED: GIRT BAR ON AFT LEFT DOOR IS HARD TO GET INTO BRACKETS, NEEDS ADJUSTMENT. REMOVED AND REPLACED AFT LT GIRT BAR ASSY DUE TO BROKEN STOP. IAW AMM 25-66-01-440-803.Oct 18, 2026 · N324RA · Boeing 7378 · Emergency EquipmentSDR IPXA2026101806238Skin · puncturedDURING WALKAROUND, FOUND A PUNCTURE AT SLAT NR 10 (WS 624). SLAT CRACKED AT SEVERAL SPOTS, NUMEROUS RIVETS SHEARED. R/R SLAT #10 (STATION 624) IAW MM 27-81-02-024. ACCOMPLISHED OPS TEST PER MM 27-81-02/501 TEST FAIL. DUE TO NO SLAT TARGETS. S296,S310 SENSOR TAOct 18, 2026 · N351UP · Boeing 76734AF · Leading Edge DevicesSDR AALA202610193105Battery · inoperativeAIRCRAFT WAS NOT GROUNDED: FWD FA JUMPSEAT FLASHLIGHT NOT WORKING. MAINTENANCE REPLACED BATTERY OK FOR SERVICE.Oct 18, 2026 · N817AW · Airbus A319132 · Emergency LightingSDR AALA202610194907Terminal · disconnectedAIRCRAFT WAS NOT GROUNDED: SEAT 20 AND 21 EMERGENCY WHITE PATHWAY LIGHT INOP. MAINTENANCE FOUND BROKEN WIRES AT SIDEWALL TERMINATION (7261VC). RETERMINATED WIRING IAW ESPM 20-44-11 AND AWM 33-51-07 OPS CHECK GOOD IAW AMM 33-51-00. ALL LIGHTS OPERATIVE.Oct 18, 2026 · N816AW · Airbus A319132 · Emergency LightingSDR AALA202610190251Relay · damagedAIRCRAFT WAS GROUNDED: ON DESCENT OUT OF 10,000 FLIGHT DECK HAD AN ELECTRICAL SMELL. DISSIPATED BY 6,000. MAINTENANCE PERFOMED GVI OF COCKPIT C/B PANELS AND ALL E&E BAYS. FOUND RELAY 7HG (LH RECIRC FAN CONTROL) DAMAGED. REPLACED RELAY 7HG IAW ESPM 20-46-50. REOct 18, 2026 · N4032T · Airbus A319115 · Air Distribution FanSDR DALA2026101905745Bottle · low pressure2L DOOR DAMPER LOW. CORRECTIVE ACTION: SERVICED DOOR ASSIST BOTTLE PER A330 AMM 52-15. (9013013) AIRCRAFT WAS GROUNDED.Oct 18, 2026 · N824NW · Airbus A330302 · Passenger/Crew DoorsSDR DALA2026101905738Line · damagedFIRE SUPPRESSION LINE DAMAGE IN NBR 1 PYLON. REPLACED PYLON FIRE SUPPRESSION LINE IAW AMM 26-21. OK FOR SVC. (1872210) AIRCRAFT WAS GROUNDED.Oct 18, 2026 · N430DX · Airbus A330941 · Extinguishing SystemSDR DALA2026101905736Fitting · damaged2 EA FITTINGS DAMAGED MPN G5451006620000 IN NBR 1 ENG PYLON. CORRECTIVE ACTION: REMOVED AND REPLACED 2 EA DAMAGED FITTINGS PER AIRBUS DRAWING G54510066. (1872237) AIRCRAFT WAS GROUNDED.Oct 18, 2026 · N430DX · Airbus A330941 · Nacelle/Pylon, Attach FittingsSDR DALA2026101905735Fitting · damagedFWD FITTING MPN G5451209120100 DAMAGED IN NBR 1 ENG PYLON. REPLACED FITTING MPN G5451209120100 PER AIRBUS DRAWING G54512091. (1872235) AIRCRAFT WAS GROUNDED.Oct 18, 2026 · N430DX · Airbus A330941 · Nacelle/Pylon, Attach FittingsSDR DALA2026101905734Seat Track · corrodedCABIN SEAT TRACK AT FR 17 TO FR 18, -Y 450 FOUND CORROSION. REPLACED SEAT TRACK PER SRM 51-72-11-911-001. (1871819) AIRCRAFT WAS GROUNDED.Oct 18, 2026 · N408DX · Airbus A330941 · Fuselage, Seat/Cargo Attach FittingsSDR DALA2026101905733Seat Track · corrodedCABIN SEAT TRACK AT FR 17 TO FR 18, -Y 953 FOUND CORROSION. REPLACED SEAT TRACK PER A330 SRM 51-72-11-911-001. (1871813) AIRCRAFT WAS GROUNDED.Oct 18, 2026 · N408DX · Airbus A330941 · Fuselage, Seat/Cargo Attach FittingsSDR ABXA20261018474A/C Pack · warning messageDURING TAXI OUT, L PACK OFF EICAS MSG AFTER ENGINE START. A/C RETURNED TO GATE (BTB) AND MTX GROUNDED A/C ,MTX DEFERRED LH PACK IAW ABX MEL 21-51-1-1. AND RETURNED A/C TO SERVICEOct 18, 2026 · N1709A · Boeing 767375 · Cabin Cooling SystemSDR IXXA20261018103Window · bindingFIRST OFFICER'S WINDOW OUT OF RIG. CLOSED INDICATION INDICATING. LOCK HANDLE BINDING AT 6 O'CLOCK POSITION. LUBED WINDOW COMPONENTS IAW B767 AMM 12-21-34. CLEANED AND LUBED WINDOW SEAL IAW B767 AMM 56-11-00. ACCOMPLISHED LATCH SYSTEM TEST IAW B767 AMM 56-11-02Oct 18, 2026 · N367AZ · Boeing 767319 · Flight Compartment WindowsSDR UIEA2026101800991Outflow Valve · faultedCRZ FLT FL 380: CABIN ALT WARNING AT 10,800 FT OBSERVED. ELEC QRH C/W. EMERGENCY DESCENT PERFORMED WITH O2 MASKS ON.(<P>REMOVED AND REPLACED LWR FWD CARGO OVERBOARD VALVE PER AMM 21-26-17/401. TEST PASSED. PERFORMED CABIN PRESSURE LEAKAGE TEST PER AMM 05-51-08Oct 18, 2026 · N852GT · Boeing 74787UF · Pressure Regulator/Outflow ValveSDR DALA2026101905723Skin · damagedFOUND A DISCREPANT FASTENER HOLE WAS IDENTIFIED AT THE INTERSECTION OF FRAME Y503 AND LONGERON L1, AT THE FOURTH FASTENER LOCATION AFT OF THE FORWARD EDGE OF STC DOUBLER, CORRECTIVE ACTION: COMPLIED WITH ER/A 637350-14AD. (1871858) (AIRCRAFT GROUNDED).Oct 18, 2026 · N980AT · Boeing 717200 · Fuselage Main, Plate/SkinSDR DALA2026101905722Oxygen Mask · faultedF/O O2 MASK-SETTINGS DO NOT ALIGN WITH INSIDE INDICATOR IE AT 100% THE INDICATOR READS EMERGENCY, R/R F/O O2 MASK PER B717 AMM 35-13. (9520956) (AIRCRAFT GROUNDED).Oct 18, 2026 · N955AT · Boeing 717200 · Crew Oxygen SystemSDR DALA2026101905721Skin · dentedFOUND DENT AT VERTICAL STABILIZER RUDDER TAP SKIN, BETWEEN ZRT=5.70 - 30.30, CORRECTIVE ACTION: COMPLIED WITH ER/A 637462-14. (1872819) (AICRAFT GROUNDED).Oct 18, 2026 · N981AT · Boeing 717200 · Rudder, Plate/SkinSDR DXTA2026101910246Precatch · faultedMAIN DOOR PRE-CATCH IS NOT AUTOMATICALLY RELEASING WHEN OPENING THE DOOR FROM EITHER INSIDE OR OUTSIDE. DOOR WILL OPEN BUT REQUIRES PRECATCH BUTTON TO BE PUSHED. INSPECTED LH MLG NOTED PAINT MESSED UP ON OLEO DUE TO A PREVIOUS LEAK BUT NO DEFECTS NOTED ON LHOct 18, 2026 · N14QS · Cessna 560XL · Emergency ExitsSDR DXTA2026101910256Fan · failedCLIMBING THROUGH FL300 WE HEARD AN OSCILLATING/BUZZING SOUND COMING FROM BEHIND THE GLARESHIELD LEFT SIDE. SHORTLY BEFORE LANDING, THERE WAS AN ASSOCIATED UNUSUAL SMELL. THIS MATCHES WITH A PREVIOUS WRITE UP. REMOVED LEFT GLARESHIELD COOLING FAN (MC001) FOR OOct 18, 2026 · N901QS · Cessna 680A · Air Distribution FanSDR DXTA2026101910259Door · bindingCABIN ENTRY DOOR IS VERY HARD TO OPEN AND CLOSE. IT IS HITTING METAL WHEN ATTEMPTING TO CLOSE. DON'T KNOW IF ITS RELATED TO THE CHECK DOOR MEL. OPERATED MAIN CABIN DOOR NUMEROUS TIMES WITH NO DEFECTS NOTED,(HARD TO OPEN OR CLOSE OR METAL HITTING). ALSO PERFOROct 18, 2026 · N976QS · Cessna 680A · Passenger/Crew DoorsSDR DXTA2026101910262Unknown · odorCLIMBING THROUGH 33,000 FT, A SUDDEN BLAST OF VERY HOT AIR AND FUME/OIL SMELL CAME THROUGH THE VENTS IN COCKPIT FOR A SECOND OR TWO AND IMMEDIATELY WENT AWAY AND CLEARED. DIVERTED TO MIV SINCE IT WAS ALREADY DUE FOR MX SAME DAY.Oct 18, 2026 · N925QS · Cessna 680A · Air Distribution SystemSDR DXTA2026101910244Light Sys · faultedEMERGENCY LIGHTS ABOVE SEATS 2L AND 3R DO NOT ILLUMINAT WHEN THE EMER LTS SWITCH IS IN ON POSITION. LIGHTS DO OPERATE WITH NORMAL CABLTS SWITCH. REMOVED FWD EMERGENCY BATTERY POWER SUPPLY P/N OFF BR9767-001 S/N OFF C0926 AND INSTALLED NEW / FWD EMERGENCY BATTOct 18, 2026 · N786QS · Bombdr BD1001A10 · Emergency LightingSDR AALA202610193802Flashlight · inoperativeAIRCRAFT WAS NOT GROUNDED: FLASHLIGHT UNDER FLIGHT ATTENDANT 2R SEAT DOES NOT WORK. MAINTENANCE REPLACED EMERGENCY FLASHLIGHT AT 2R JUMPSEAT PER AMM 25-65-00.Oct 18, 2026 · N990AU · Airbus A321231 · Emergency EquipmentSDR AALA202610199324Wire Harness · looseAIRCRAFT WAS NOT GROUNDED: SEAT 22ABC EMERGENCY ESCAPE PATH LIGHT INOP. MAINTENANCE RESECURED EMERGENCY LIGHTS HARNESS AT ROW 22ABC PER AWM 33-51-00. OPS CHECK GOOD OK FOR SERVICE.Oct 18, 2026 · N914UY · Airbus A321231 · Light System WiringSDR AALA202610194708Wire Harness · looseAIRCRAFT WAS NOT GROUNDED: SEAT 21ABC EMERGENCY ESCAPE PATH LIGHT INOP. MAINTENANCE RESECURED EMERGENCY LIGHTS HARNESS AT ROW 21ABC PER AWM 33-51-00. OPS CHECK OK FOR SERVICE.Oct 18, 2026 · N914UY · Airbus A321231 · Light System WiringSDR AALA202610195038Wire Harness · looseAIRCRAFT WAS NOT GROUNDED: CEILING EMERGENCY PATH LIGHT AT SEAT ROW 12 INOPERATIVE. MAINTENANCE RESECURED EMERGENCY LIGHTS HARNESS AT ROW 21ABC PER AWM 33-51-00. OPS CHECK OK FOR SERVICE.Oct 18, 2026 · N914UY · Airbus A321231 · Light System Wiring