Boeing 767-3S1

Service difficulty reports · 974

Newest first. 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'
  WHERE aircraft_model_key = '7673S1'
  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 UIEA2021121402455Latch · none# 1 ENG. NACELLE STRUT L/H SAILBOAT FAIRING ACCESS DOOR ( PNL 437BL ) WITH TWO LATCH DAMAGED .(<P>REMOVED & REPLACED DAMAGED LATCH AT #2 ENG STRUT I/B FAIRING ACCESS DOOR IAW B767-300</P> / <P>AMM 54-53-02</P>)Dec 17, 2021 · N640GT · Boeing 7673S1 · Nacelle/Pylon, Main FrameSDR UIEA2021121402456None · none# 1 ENG. NACELLE STRUT T/E FAIRING WITH SCREWS M(<P><SPAN>INSTALLED MISSING FASTENERS AT # 1 ENG. NACELLE STRUT T/E FAIRING IAW B767-300 SRM 51-40-02.</SPAN></P>)Dec 17, 2021 · N640GT · Boeing 7673S1 · Nacelle/Pylon, Main FrameSDR UIEA2021121402457None · none# 2 ENG. NACELLE STRUT SEVERALS SCREWS MISSING IN ACCESS PNLS.(<P>INSTALLED MISSING FASTENERS AT # 2 ENG. NACELLE STRUT ACCESS PANELS IAW B767-300 SRM 51-40-02.</P>)Dec 17, 2021 · N640GT · Boeing 7673S1 · Nacelle/Pylon, Main FrameSDR UIEA2021121402458Evas Unit · noneCOCKPIT F/O EVAS DUE TIME CHANGE DUE 25 MAR 22(<P>REMOVED AND REPLACED COCKPIT F/O EVAS IAW B767-300 AMM 20-60-99.</P>)Dec 17, 2021 · N640GT · Boeing 7673S1 · Communications SystemSDR UIEA2021121402460Kit · noneM/D FIRST AID KIT DUE TIME CHANGE P/N S6-01-0005-306 NSN DUE 01 JAN 22 .(<P>REMOVED & REPLACED FIRST AID KIT L/H AFT OVHD BIN PER AMM 25-64-00. CK'D OK .</P> / <P>EXP. TAG. P/N S6-01-0005-306</P>)Dec 17, 2021 · N640GT · Boeing 7673S1 · Life RaftSDR UIEA2021121402461None · noneRH MLG SCRAPER SEAL DISLODGED .(<P>REMOVED & REPLACED RH MLG SEALS PER AMM 32-11-25. OPS CHECK GOOD PER 32-32-00.</P> / <P>NO LEAKS NOTED</P>)Dec 17, 2021 · N640GT · Boeing 7673S1 · Powerplant SystemSDR UIEA2021112902441None · noneL1 DOOR FIRST AID KIT USED / ( EMERGENCY MEDICAL EQUIPMENT, FIRST AID KIT (FAK) AND/OR ASSOCIATED EQUIPMENT, NOT REQUIRED BY FAR )(<P>REMOVED AND REPLACED 1ST AID KIT IAW ATLAS AIR GMM 3.40.1-2 THIS CLEARS MDDR 157404</P>)Nov 24, 2021 · N640GT · Boeing 7673S1 · Emergency Locator BeaconSDR UIEA2021111302410None · none"R" ENG ANTI-ICE VALVE DISCRETE LIGHT ILLUMINATED(<P>ACCOMPLISHED RT ENG INLET TAI VALVE OPS CK PER AMM 30-21-03-714-062. RT EAI VALVE LIGHT OPS CKS OK.</P>)Nov 13, 2021 · N640GT · Boeing 7673S1 · Ice/Rain Protection SystemSDR UIEA2021111102399None · noneAPU - FAULT EICAS(<P>ACCOMPLISHED APU BITE AS PER FIM 49-11 TREE 958. AND NO FAULT FOUND. RESET APU AND STARTS OK AS PER AMM 49-11-00.</P>)Nov 12, 2021 · N640GT · Boeing 7673S1 · Airborne Auxiliary Power Unit (APU) SystemSDR UIEA2021101202221None · noneR ENG HPSOV INOP ( (HPSOV) (SECURED CLOSED) )(<P>DEFERRED INOP AS PER MEL 36-11-02-02, CAT C, MDDR 154961, ASSIGNED ACTIONS C/W.</P> / <P>17OCT-BWI MX: LP 1474431, ITEM M6: R&R CONTROL ASSY. FOR RH HPSOV IAW AMM 36-11-08. OPS CHECK GOOD. NO LEAKS & NO FAULTS OOct 11, 2021 · N640GT · Boeing 7673S1 · Pneumatic SystemSDR UIEA2021100502186Valve · noneDESCENDING THROUGH 4000 FEET R ENG HPSOV EICAS MESSAGE DISPLAYED. ACCOMPLISHED ASSOCIATED QRH PROCEDURE.(<P>DEFERRED INOP AS PER MEL 36-11-02-02, CAT C (M) ACTIONS COMPIED WITH (RT HPSOV LOCKED OUT). MDDR #154596 ASSIGNED. STR @ 0841Z.</P> / <P>09OCT21 - 13148Oct 5, 2021 · N640GT · Boeing 7673S1 · Pneumatic SystemSDR UIEA2021101102216None · noneAPU FAULT EICAS MSG(<P>INSPECTED APU FOR SUFFICIENT OIL, NO OIL NEEDED. PERFORMED APU BITE TEST AND SELF TEST IAW AMM TASKS. FOUND CLEARED MEMORY THEN RAN APU IAW AMM TASK 49-11-00-802-002. NO FAULTS FOUND.</P>)Oct 5, 2021 · N640GT · Boeing 7673S1 · Airborne Auxiliary Power Unit (APU) SystemSDR UIEA2021092602120Sensor · warning messageR ENG HPSOV STATUS MESSAGE DISPLAYED.(<P>TRANSFERED TO MDDR 154127 PER MEL 36-11-02-02, CAT "C", DUE DATE: 06OCT21.BWI STA, 29SEP: LP 1314128, ITEM M9: REMOVED AND REPLACED RT ENG FAN AIR TEMP SENSOR IAW 767 AMM 36-11-17. OPS TEST GOOD. DMI CLEARED, PLACARDS RSep 26, 2021 · N640GT · Boeing 7673S1 · Pneumatic Distribution SystemSDR UIEA2021092702132Connector · not seatedRIGHT ENGINE FIRE LOOP 2 ( ENGINE FIRE DETECTION SYSTEMS, DETECTION LOOPS (ER RESTRICTED 120 MIN) FOUND PIN 10 UNSEATED AT CONNECTOR D2852 ON LOOP 2 FIRE CARD M684. RESEATED PIN 10 PER WD 26-21-21 AND SWPM 20. PERFORMED OPS CHECK OF FIRE DETECTION SYSTEM PER Sep 24, 2021 · N640GT · Boeing 7673S1 · Fire Protection System WiringSDR UIEA2021092302096Engine · bird ingestionMULTIPLE BIRD STRIKES ON TAKEOFF AND LANDING. (AIR TURNBACK TO ROZ)(<P>PERFORMED BIRD STRIKE CONDITIONAL INSPECTION PER B767 AMM 05-51-18-212. RH ENGINE REMOVED AND REPLACED PER ATLAS AIR W/C, 4 SMALL PUNCTURES WERE REPAIRED IN LH & RH T/R HALVES PER AMM. NO Sep 24, 2021 · N640GT · Boeing 7673S1 · Turbine Engine Air Inlet SectionSDR UIEA2021092602118Shutoff Valve · inoperativeL PACK TEMP ON EICAS - L PACK CURRENTLY IN "N STBY". LEFT PACK WILL NOT TURN OFF, NO EICAS MESSAGE OR PACK OFF LIGHT.(<P>TRANSFERRED TO MDDR #154085. PLACED ON MEL 21-51-03-02. CAT C . DUE DATE 05OCT21 PLACARDS INSTALLED. MCC NOTIFIED.</P> / <P>LP 1314107 - HHSep 24, 2021 · N640GT · Boeing 7673S1 · Cabin Cooling SystemSDR UIEA2021092202071Circuit Card · faultedSTATUS R ENG FIRE LP 1. REMOVED AND REPLACED MID274 LOGIC TEST FIRE/OVHT CARD IAW AMM 26-10-01. PERFORMED FIRE/OVHT TEST IAW AMM 26-11-01. OPS CHECK GOOD AT THIS TIME.Sep 16, 2021 · N640GT · Boeing 7673S1 · Fire DetectionSDR UIEA2021091102005Fault Message · false activationAPU FAULT MAX EGT 778 RPM 39(<P>PERFORMED APU ECU BITE CHECK IAW 49-61-05. NO FAULTS PRESENT. PERFORMED OPERATIONAL CHECK OF APU IAW AMM 49-11-00. NO DEFECTS NOTED AT THIS TIME.</P>)Sep 9, 2021 · N640GT · Boeing 7673S1 · APU Indicating SystemSDR UIEA2021091102006Logic Card · faultedSTATUS R ENG FIRE LP 1(<P>REMOVED AND REPLACED MID274 LOGIC TEST FIRE/OVHT CARD IAW AMM 26-10-01. PERFORMED FIRE/OVHT TEST IAW AMM 26-11-01. OPS CHECK GOOD AT THIS TIME.</P>)Sep 9, 2021 · N640GT · Boeing 7673S1 · Fire DetectionSDR UIEA2021090701982Circuit Card · not seatedRT ENG FIRE LOOP 1 STATUS MESSAGE ( ENGINE FIRE DETECTION SYSTEMS, DETECTION LOOPS (ER RESTRICTED 120 MIN) )(<P>TRANSFERRED TO MEL 26-11-01-01, MDDR 153007, CAT C, DUE ON 14 SEP21 </P> / <P>LP 1484434 ITEM 6: RESEATED M10274 LOGIC TEST FIRE /OVHT CARD IN P54 Sep 3, 2021 · N640GT · Boeing 7673S1 · Fire DetectionSDR UIEA2021090201940Actuator · failedLEFT PACK AUTO FUNCTION INOP ( PACK TEMPERATURE CONTROL SYSTEMS (-200/-300) , AUTO MODE), PLACARD INSTALLED. 1484465/21/BWI- REMOVED AND REPLACED LEFT PACK LOW LIMIT VALVE (V131) IAW AMM 21-51-11. OPERATIONAL CHECK GOOD, AUTO AND MANUAL MODES FUNCTION NORMALLYSep 1, 2021 · N640GT · Boeing 7673S1 · Cabin Cooling SystemSDR UIEA2021083101925Skin · dented2 ENG. INLET CASE HAS A DENT OUT OF LIMITS @ 11 O'CLOCK POSITION, MEASURED DENT AT NR 2 ENG INLET AT THE 11 O'CLOCK POSITION, FOUND MAX DEPTH TO BE .070". FOUND TO BE OUT OF LIMITS IAW SRM 54-12-01-1A, ALLOWABLE DAMAGE 1, FIG 101. REMOVED AND REPLACAug 31, 2021 · N640GT · Boeing 7673S1 · Engine Air Intake SystemSDR UIEA2021083101924Seal · loose#2 ENG FAN CASE FWD SIDE HAS LOOSE SEAL AND REQUIRES SEAL TO BE SECURED PRIOR TO INLET CASE IN STALLATION(<P>LOCATED CLEANED AND RESECURED LOOSE SEAL AT # 2 ENG. BY FAN CASE PER B767-300 AMM 72-33-00-308-038-H00.</P>)Aug 31, 2021 · N640GT · Boeing 7673S1 · Engine (Turbine/Turboprop)SDR UIEA2021083101923Bottle · damagedFIRE BANE - EXTIINGUISHING AGENT BOTTLE DAMAGED P/N LKFD RH LAST OVHD BIN(<P>REMOVED AND REPLACED FIREBANE - EXTINGUISHING AGENT AT RH LAST OVHD BIN AS PER </P> / <P>B767-300 AMM 25-60-00.</P>)Aug 31, 2021 · N640GT · Boeing 7673S1 · Extinguishing SystemSDR UIEA2021083101922Sealant · deterioratedENG #2 I/B T/REV INTERIOR FIRE RESISTANT SEALENT DETERIORATED ON AFT BOTTOM AREA(<P>REPAIRED DETERIORATED ABLATIVE MATERIAL AT #2 ENG I/B T/R IAW B767-3 AMM 78-31-00.</P>)Aug 31, 2021 · N640GT · Boeing 7673S1 · Engine Thrust ReverserSDR UIEA2021083101921Screw · missing# 2 ENGINE I/B PYLON ACCESS PANEL MISSING SCREW(<P>REPLACED MISSING SCREW AT #2 ENG. I/B PYLON ACCESS PANEL IAW B767-3 SRM 57-40-02.</P>)Aug 31, 2021 · N640GT · Boeing 7673S1 · Nacelle/Pylon, Plate/SkinSDR UIEA2021083101919Cylinder · low pressureSERVICE CREW OXYGEN CYLINDER TO FULL(<P>SERVICED CREW OXYGEN CYLINDER AT LOWER E&E COMPARTMENT AS PER B767-300 AMM 12-15-08-603-001,</P> / <P>AMM 35-00-00-912-005, AMM 35-11-00-206-233 ADVISORY CIRCULARS. AC 43.13-1B PART 9-46 THRU 9-51</PAug 31, 2021 · N640GT · Boeing 7673S1 · Crew Oxygen SystemSDR UIEA2021083001915Relay · inoperativeLEFT PACK TEMP AUTO CONTOL INOP ( PACK TEMPERATURE CONTROL SYSTEMS (-200/-300) , AUTO MODE )(<P>T/S TO FAULTY LF PACK AUTO/MANUAL RELAY K57. REMOVED AND REPLACED RELAY 57 AS PER SWPM 20-81-22 AND SSM 21-50-03 AND PERFORMED OPS CHECK OF LF PACK COOLING SYSTEM PAug 28, 2021 · N640GT · Boeing 7673S1 · Cabin Cooling SystemSDR UIEA2021082801903Indication Sys · intermittentEICAS L PACK TEMP INTERMITTENT IN FLIGHT(<P>PERFORMED TEMP CONTROLLER BITE IAW AMM 21-51-14. NO FAULTS FOUND OPS CKS NORMAL . NO EICAS MSG</P>)Aug 27, 2021 · N640GT · Boeing 7673S1 · Cabin Cooling SystemSDR UIEA2021082301844Blade · distortedON POST FLT INSP FOUND LEFT ENG #19 FAN BLADE DISTORTED DUE TO BIRD STRIKE. (3.5" IN LENGTH, .1875" DISPLACEMENT). DAMAGE WITHIN LIMITS PER AMM 72-31-02-226-012-H00.(<P>TRANSFERRED TO NON-MEL 152205.</P> / <P>LP 1314192 ITEM 3: LEFT ENGINE FAN BLADE # 19 REQUIAug 20, 2021 · N640GT · Boeing 7673S1 · Turbine Engine Compressor SectionSDR UIEA2021081101766Warning Light · false activationAFTER ENGINE SHUTDOWN "R AC BUS OFF" EICAS, RIGHT AC BUS ISLN. AFTER RESET, OPS NORMAL(<P>ACCOMPLISHED BPCU BITE PERIODIC TEST AS PER AMM 24-22-00-745-004 AND NO FAULTS FOUND, OK FOR CONTINUED SVC, OPS OK PER AMM TASK 24-22-00-715-044</P>)Aug 8, 2021 · N640GT · Boeing 7673S1 · AC Power Distribution SystemSDR UIEA2021080601722Actuator · faultedLEFT PACK TEMP EICAS ON PUSHBACK(<P>DEFERRED AUTO MODE INOP AS PER MEL 21-51-03-01, CAT C, MDDR # 151386 ASSIGNED </P> / <P>LP 1314146 ITEM 9 - MIA - REMOVED AND REPLACED RAM AIR INLET DOOR ACTUATOR IAW 21-53-03. OPS CHECK GOOD. THIS CLOSES MDDR 151386. PLACARAug 6, 2021 · N640GT · Boeing 7673S1 · Cabin Cooling SystemSDR UIEA2021080651707Warning Light · false indicationBOTH CENTER FUEL PUMPS PRESSURE LIGHTS EXTINGUISHED WITH FUEL IN CENTER TANK AND ENGINES SHUT DOWN(<P>ACCOMPLISHED FIM 28-22-05 AND NO FAULTS FOUND , ACCOMPLISHED GFI RELAY OPS TEST AND TEST OK PER AMM 28-22-00-715-096, ALSO FOUND AMM 28-42-00/001, VERIFIED A/Aug 4, 2021 · N640GT · Boeing 7673S1 · Fuel Boost PumpSDR UIEA2021080501709Warning Light · false indicationAPU FWD LPVHP PRESSURE LIGHT IS ON WHILE APU WORKING(<P>ACOMPLISHED TEST OF APU FUEL FEED SYS AS PER 28-25-00. AND OPS CK OK, NO FAULTS FOUND</P>)Aug 4, 2021 · N640GT · Boeing 7673S1 · APU Engine Fuel and ControlSDR UIEA2021071001507Warning Message · illuminatedEQUIPMENT COOLING EICAS ANNUNCIATED ON CLIMB OUT- QRH COMPLIED WITH.(<P>PERFORMED B767 FIM 21-58 FT 913 BLOCK 1, 2, 4, 6. STS OK FOR SERVICE.</P>)Jul 10, 2021 · N640GT · Boeing 7673S1 · Air Distribution SystemSDR UIEA2021070801490Actuator · malfunctionedDUE TO RT PIMU (353 18-A VSV FEEDBACK) FAULT, RT ENG CONTROL EICAS WILL APPEAR INTERMITTANTLY. PLEASE T/S WITH FIM 73-21 TREE 878 AND FIM 71-01 TASKS A61-A62.(<P>T/S PER FIM 73-21 FT 878 AND 71-00-00 AMM TEST #12 EEC ECU ACTUATORS - FOUND TEST #12 FLT CH. A FAJul 6, 2021 · N640GT · Boeing 7673S1 · Fuel Controlling SystemSDR UIEA2021062801435Fan · failedDURING POST FLIGHT INSP. FOUND L/H RECIP. FAN SWITCH WILL NOT LATCH.(<P>TRANSFERRED TO MEL 21-25-01-01, CAT C. DMI # CL0161, CONVERTED TO MDDR 149279. DUE DATE 06JUL21 MCC: STR, 0329Z.</P> / <P>01 JUL 21 - 1484623 - ITEM# 9 - BWI - REMOVED AND REPLACED LEFT REJun 27, 2021 · N640GT · Boeing 7673S1 · Air Distribution FanSDR UIEA2021062501414Pbe · failedPBE AT LH DOOR INDICATOR BAD.(<P>TRANSFERRED TO MDDR 149127 MEL 35-20-01. VERIFIED 5 SERVICEABLE UNITS REMAIN ABOARD. CAT D, DUE DATE 22OCT21. T&I: 1212Z CW.</P> / <P>LP 1140109, ITEM M13: REMOVED & REPLACED PBE AT L4 DOOR. THIS CLEARS DMI 149127. REF AMM 25-6Jun 24, 2021 · N640GT · Boeing 7673S1 · Emergency EquipmentSDR UIEA2021052101162Apu · unknown"APU FAULT" APU WON'T START ON GROUND, HUNG START AT 17%.(<P>TROUBLESHOT APU START FAULT. APU FAULTED @ 7% START. FAULT CLEARED, APU STARTED NORMAL. BATTERY START. APU BATT VOLTAGE 28VDC DIPPED TO 24 VDC. BATT REGAINED 28VDC @ 13 AMPS</P>)May 21, 2021 · N640GT · Boeing 7673S1 · APU Core EngineSDR UIEA2021050301057Isolation Valve · inoperativeLEFT ISOLATION VALVE INOP VALVE DISAGREE LIGHT(<P>REMOVED AND REPLACED LEFT ISOLATION VALVE IAW AMM 36-11-04. OPS CHECK GOOD.</P>)Apr 29, 2021 · N640GT · Boeing 7673S1 · Pneumatic Distribution SystemSDR UIEA2021043001031Isolation Valve · inoperativeLEFT ISOLATION VALVE INOP. VALVE DISAGREE LIGHT. REMOVED AND REPLACED LEFT ISOLATION VALVE IAW AMM 36-11-04, OPS CHECK GOOD.Apr 29, 2021 · N640GT · Boeing 7673S1 · Pneumatic Distribution SystemSDR UIEA2021042701011Transmitter · faultedAPU OIL QTY IND INTERMITTANTLY DROPS BETWEEN 75% AND 25% DURING START, VERY SLOW TO SPOOL UP THEN ABORTS START.(<P>REMOVE AND REPLACED APU OIL QTY TRANSMITTER REF AMM 49-94-04. OPS CHECK OK, LEAK CHECK OK.</P>)Apr 26, 2021 · N640GT · Boeing 7673S1 · APU Oil SystemSDR UIEA2021041200879Modulating Valve · faultedFLIGHT DECK TEMP INOP IN AUTO MODE(<P>REMOVED AND REPLACED TRIM AIR MODULATING VALVE IAW B767 AMM 21-61-07. OPS CHECK GOOD AT THIS TIME.<BR /></P>)Apr 8, 2021 · N640GT · Boeing 7673S1 · Cabin Temperature Control SystemSDR UIEA2021040900870Warning Message · false activationITEM #1 EICAS MSG FLT DECK TEMP.(<P>ACCOMPLISHED BITE CK OF TEMP CONTROL LEFT PACK, NO FAULTS FOUND, MSG RESET IAW B767 AMM 27-61-00. FLT DECK TEMP OPS CK GOOD AT THIS TIME. NO MSGS.</P>)Apr 8, 2021 · N640GT · Boeing 7673S1 · Cabin Temperature Control SystemSDR UIEA2021032100653Cradle · inoperativeMAIN CABIN L-4 FLT ATTEND HANDSET CRADLE INOP.(<P>REMOVED AND REPLACED MAIN CABIN L-4 FLT ATTEND HANDSET CRADLE IAW AMM 23-42-01. OPS CHECK GOOD.</P>)Mar 23, 2021 · N640GT · Boeing 7673S1 · Interphone/Passenger Announcement (PA) SystemSDR UIEA2021032100654Power Supply · inoperativeUPPER RED ANTI-COLLISION LIGHT INOP.(<P>REMOVED/REPLACED PPER BEACON PWR SUPPLY M570 AND OPS BEACON LT SYS PER AMM 33-44-04.</P><P>MDDR 143807 CLEARED UP / PLACARD REMOVED.</P>)Mar 23, 2021 · N640GT · Boeing 7673S1 · Exterior LightingSDR UIEA2021032100655Module · not reportedCOCKPIT LEFT (PILOT) SIDE EVAS DUE FOR O/H P/N 107 STC 019 S/N 052 DD 05P.(<P>REMOVED & REPLACED CAPT'S EVAS MODULE PER AMM 25-60-99.</P><P>P/N OFF 107STC-019 S/N 052DD05P S/N ON 131EE03P0.</P><P>5Y2853700</P>)Mar 23, 2021 · N640GT · Boeing 7673S1 · Emergency EquipmentSDR UIEA2021032100656Line · leakingR/H ANTI SKID MODULE LEAKING HYDRAULIC FLUID P/N 274T1102-2(<P>RETORQUED HYDRAULIC LINES IAW 32-42-02. PERFORMED LEAK CHECK IAW 29-11-00.</P><P>NO LEAKS NOTED.</P>)Mar 23, 2021 · N640GT · Boeing 7673S1 · Hydraulic System, MainSDR UIEA2021032100657Sensor · inoperativeCOCKPIT ON EICAS ECS PAGE "L PACK PRIIM HEAT EX IN" SHOWS NO DATA P/N MS 28034-1(<P>REMOVED/REPLACED L PRJ. HEAT EXCHANGER INLET TEMP SENSOR AND OPS CHECK OK AMM 21-52-08.<BR /></P>)Mar 23, 2021 · N640GT · Boeing 7673S1 · Cabin Cooling SystemSDR UIEA2021032100658Sensor · malfunctionedCOCKPIT ON EICAS ECS PAGE "R PACK COOL OUT" SHOWS NO DATA P/N 1122599(<DIV>REMOVED/REPLACED PRECOOLER OUT TEMP SENSOR & OPS CHECK OK IAW AMM 36-22-02</DIV>)Mar 23, 2021 · N640GT · Boeing 7673S1 · Pneumatic Distribution System
Back to Boeing 767-3S1