# JASC 7421: Spark Plug/Igniter

- Type: JASC system/component code (FAA)
- ATA chapter: 74 Ignition
- Title in the code table: SPARK PLUG/IGNITER
- Service difficulty reports: 703
- FAA code table: https://www.faa.gov/sites/faa.gov/files/JASC_Code.pdf#page=64
- Page: https://openairdocs.org/jasc/7421

## What it covers

The part which provides the spark in the reciprocating engine cylinders or combustion chamber of turbine engines.

## Service difficulty reports (703, newest 50)

- [SDR 2026FA0000783](https://openairdocs.org/sdr/2026FA0000783), Sep 23, 2026: Beech P35. SPARK PLUG. SEPARATION. DURING CRUISE FLIGHT, THE AIRCRAFT EXPERIENCED AN IMMEDIATE PARTIAL LOSS OF ENGINE POWER ACCOMPANIED BY SEVERE ENGINE RO (N1721G)
- [SDR I5PA2026083068807](https://openairdocs.org/sdr/I5PA2026083068807), Aug 30, 2026: Boeing 757230. IGNITER. WORN. ETOPS SIGNIFICANT REPORT, RT ENGINE UPPER IGNITER PLUG WORN. REPLACED IGNITER PLUG IAW AMM. (N688SL)
- [SDR YENA2026082400697](https://openairdocs.org/sdr/YENA2026082400697), Aug 22, 2026: Airbus A321271NX. IGNITER. FAULTED. FLT 346, BCN-BOS. (ETOPS) NR 2 ENGINE IGN B FAULT, R & R ENG #2 IGN B IGNITER PLUG IAW AMM 74-21-01-400-801-A. OPS CHK O (N4073J)
- [SDR 2026F00175](https://openairdocs.org/sdr/2026F00175), Aug 13, 2026: Dhav DHC3. IGNITER. BURNED. IGNITORS BURN THROUGH TO ELECTRICAL LEAD WITHIN 100 HOURS OF USE. HOT TURBINE COMBUSTION GASES ESCAPE THROUGH IGNITOR BO (N510PR)
- [SDR I5PA2026081019302](https://openairdocs.org/sdr/I5PA2026081019302), Aug 10, 2026: Boeing 757223. IGNITER. FAULTY. RIGHT ENGINE IGNITION SYSTEM INOPERATIVE. REPLACED RT ENGINE IGNITER PLUGS IAW AMM (N193AN)
- [SDR I5PA2026080819301](https://openairdocs.org/sdr/I5PA2026080819301), Aug 8, 2026: Boeing 757223. IGNITER. FAULTY. LEFT ENGINE IGNITION SYSTEM INOPERATIVE. REPLACED LT ENGINE IGNITER PLUGS IAW AMM. (N193AN)
- [SDR YENA2026080500652](https://openairdocs.org/sdr/YENA2026080500652), Aug 5, 2026: Airbus A321271NX. IGNITER. NOT REPORTED. FLT 2220, LHR-JFK. (ETOPS) IGNITER PLUGS REQ REPLACEMENT; R & R IGNITER PLUGS IAW AMM 74-21-41, OPS CHKD NORMAL ACFT OK  (N4062J)
- [SDR SWAA2026080515446](https://openairdocs.org/sdr/SWAA2026080515446), Aug 1, 2026: Boeing 7377H4. IGNITER. FAULTED. ABORTED NR 2 ENGINE START. IGNITION, RT N1, STALLED AT APPROX 9% TEMP 550. ENGINE STARTED OK WITH START SWITCH IN BOTH,  (N435WN)
- [SDR ECPR20260731002](https://openairdocs.org/sdr/ECPR20260731002), Jul 30, 2026: Piper PA28R201. SPARK PLUG. CRACKED. FOLLOWING DISCOVERY OF A CRACKED SPARK PLUG ON ANOTHER AIRCRAFT, A PRECAUTIONARY INSPECTION WAS CONDUCTED OF THE SPARK P (N8585Z)
- [SDR 2026FA0000612](https://openairdocs.org/sdr/2026FA0000612), Jul 30, 2026: Mooney M20M. SPARK PLUG. CRACKED. SPARK PLUGS, TEMPEST: UPON REMOVAL, 4 OF THE 12 SPARK PLUGS, FOUND TO HAVE CIRCUMFERENTIAL CRACKS IN STEEL SHELL, LOCATE (N530JP)
- [SDR ECPR20260731001](https://openairdocs.org/sdr/ECPR20260731001), Jul 27, 2026: Piper PA28161. SPARK PLUG. CRACKED. A SPARK PLUG WAS REPLACED DURING A SCHEDULED MAINTENANCE INSPECTION. DURING THE POST-MAINTENANCE OPERATIONAL CHECK, THE  (N555PU)
- [SDR 2026FA0000579](https://openairdocs.org/sdr/2026FA0000579), Jul 14, 2026: Cessna 525A. IGNITER. NO TEST. IGNITORS FAILED TO TEST (N785MT)
- [SDR DALA2026061603614](https://openairdocs.org/sdr/DALA2026061603614), Jun 14, 2026: Boeing 757232. IGNITER. FAULTY. ABORTED ENGINE START RIGHT ENGINE, STRONG FUEL SMELL IN CABIN. MAINT ADVISED START AGAIN ON BOTH IGNITORS, WITH NORMAL S (N685DA)
- [SDR YENA2026051500458](https://openairdocs.org/sdr/YENA2026051500458), May 13, 2026: Airbus A321271NX. IGNITER. FAULTED. FLT 1107, JFK-LHR.(ETOPS) DURING ENGINE 1 START WE GOT MESSAGE ENG 1 IGN A FAULT; R/R ENG 1 IGNITER A & B IAW AMM 74-21- (N4058J)
- [SDR I5PA2026042319301](https://openairdocs.org/sdr/I5PA2026042319301), Apr 23, 2026: Boeing 757223. IGNITER. FAILED. FLIGHT MGE410, LEFT ENGINE IGNITION SYSTEM INOP. REPLACED SYS 1 AND 2 IGNITERS. (N193AN)
- [SDR YENA2026042300424](https://openairdocs.org/sdr/YENA2026042300424), Apr 21, 2026: Airbus A321271NX. EXCITER. FAULTED. FLT# 1620. BOS-LHR. (ETOPS) "ENG 2 IGN B FAULT ( IGNITION SYSTEMS B) SYSTEM B ). REPLACED ENG 2 IGN EXICTER PER AMM 74-1 (N4058J)
- [SDR CALA2026042415693](https://openairdocs.org/sdr/CALA2026042415693), Apr 20, 2026: Boeing 7673CB. IGNITER. FAULTED. ON FIRST ENGINE START ATTEMPT ON LEFT ENGINE WITH ENGINE START IGNITER IN NO. 2 POSITION. NO ENGINE VALVE LIGHT WITH NO  (N684UA)
- [SDR I5PA2026033075710](https://openairdocs.org/sdr/I5PA2026033075710), Mar 30, 2026: Boeing 75729J. IGNITER. WORN. FLIGHT MGE301, RIGHT ENGINE HUNG START. FOUND UPPER IGNITER PLUG WORN TO LIMITS. REPLACED IGNITER PLUG PER AMM. (N757QM)
- [SDR YENA2026033000351](https://openairdocs.org/sdr/YENA2026033000351), Mar 28, 2026: Airbus A321271NX. IGNITER. FAILED. FLT 724 LAX-JFK (ETOPS), ENG 1 IGNITION A FAULT ( IGNITION SYSTEMS A) SYSTEM A ). REPLACED ENG 1 IGNITER PLUG IAW AMM 74 (N2151J)
- [SDR I5PA2026032019304](https://openairdocs.org/sdr/I5PA2026032019304), Mar 20, 2026: Boeing 757223. IGNITER. FAULTED. FLIGHT MGE301. LEFT ENGINE NO LIGHT OFF. R & R LEFT ENGINE NR 1 IGNITER IAW AMM. (N193AN)
- [SDR I5PA2026030719302](https://openairdocs.org/sdr/I5PA2026030719302), Mar 7, 2026: Boeing 757223. IGNITER. WORN. RIGHT ENGINE IGNITER PLUGS FOUND OUT OF LIMITS DURING INSPECTION. REPLACED RT IGNITER PLUGS PER AMM. (N193AN)
- [SDR YENA2025120901185](https://openairdocs.org/sdr/YENA2025120901185), Dec 7, 2025: Airbus A321271NX. IGNITER. FAULTED. FLT 2220, LHR-JFK. (ETOPS) ENG 2 ING B FAULT ON TOUCHDOWN, REMOVED AND REPLACED ENG NR 2 IGNITER PLUG B (LOWER) IAW AMM  (N4048J)
- [SDR YENA2025112601123](https://openairdocs.org/sdr/YENA2025112601123), Nov 25, 2025: Airbus A321271NX. IGNITER. DAMAGED. FLT#2116, SFO-JFK. (ETOPS) "DMG FOUND TO LOWER IGNITER; REMOVED AND REPLACED LOWER IGNITER IAW AMM 74-21-01. OPS TEST OK (N2169J)
- [SDR NACA2025101000006](https://openairdocs.org/sdr/NACA2025101000006), Oct 10, 2025: Boeing 76733A. IGNITER. WORN. NR 2 ENGINE UPPER IGNITER PLUG WORN BEYOND LIMITS. REMOVED AND REPLACED NR 2 UPPER IGNITER PLUG IAW AMM 74-21-02-004-001 (N567NC)
- [SDR NACA2025101000005](https://openairdocs.org/sdr/NACA2025101000005), Oct 10, 2025: Boeing 76733A. IGNITER. WORN. NR 2 ENG LOWER IGNITER PLUG WORN BEYOND LIMITS. REMOVED AND REPLACED NR 2 LOWER IGNITER PLUG IAW AMM 74-21-02-004-001-N0 (N567NC)
- [SDR HALA20251002298](https://openairdocs.org/sdr/HALA20251002298), Oct 1, 2025: Airbus A321271N. IGNITER. DAMAGED. ETOPS - DURING T/C 321-724000-W2-1 FOUND ENG 2 LOWER IGNITER DAMAGED. REMOVED AND REPLACED IGNITER PER AMM 74-21-00. OPS (N227HA)
- [SDR NACA2025093000006](https://openairdocs.org/sdr/NACA2025093000006), Sep 30, 2025: Boeing 76733A. IGNITER. WORN. NR 1 ENG. SYS. 1 TOP IGNITION EXCITER PLUG IS WORN BEYOND LIMITS. IGNITER PLUG REPLACED IAW AMM 74-21-02-404-014-N00. (N567NC)
- [SDR NACA2025092300001](https://openairdocs.org/sdr/NACA2025092300001), Sep 23, 2025: Boeing 76733A. IGNITER. WORN. NR 1 ENG IGNITOR PLUG FOR SYSTEM 2 (BOTTOM PLUG) IS WORN BEYOND LIMITS. IGNITER PLUG REPLACED IAW AMM 74-21-02-404-014-N (N567NC)
- [SDR YENA2025009000907](https://openairdocs.org/sdr/YENA2025009000907), Sep 1, 2025: Airbus A321271NX. IGNITER. FAULTED. FLT#1908, CDG-JFK. (ETOPS) "MX SMOKE CLASS 2 MSG IN DISPLAY ( CLASS II MAINTENANCE MESSAGES DISPLAYED ON ECAM STATUS PAG (N2169J)
- [SDR YENA2025009000903](https://openairdocs.org/sdr/YENA2025009000903), Sep 1, 2025: Airbus A321271NX. IGNITER. FAULTED. FLT#2104, BOS-LGW. (ETOPS) "ECAM MSG ENG 2 IGN B FAULT ( IGNITION SYSTEMS B) SYSTEM B ); PER TSM 74-00-00-810-832-A RESE (N2169J)
- [SDR HALA20250825259](https://openairdocs.org/sdr/HALA20250825259), Aug 22, 2025: Airbus A321271N. IGNITER. WORN. ETOPS - DURING IGNITER SEGMENT INSPECTION, FOUND BOTTOM IGNITER PLUG WORN BEYOND LIMITS ON ENGINE #2. REMOVED AND REPLAC (N228HA)
- [SDR HALA20250819254](https://openairdocs.org/sdr/HALA20250819254), Aug 18, 2025: Airbus A321271N. IGNITER. FAULTED. ETOPS - ENG 1 A ING ECAM ON ENGINE START UP. REMOVED AND REPLACED LOWER IGNITER PLUG. PER AMM 74-21-01. OPS TEST BAD. FU (N215HA)
- [SDR UOIA202506300001](https://openairdocs.org/sdr/UOIA202506300001), Jun 30, 2025: Bnorm BN2A8. SPARK PLUG. FAULTED. DURING CLIMB PILOT NOTICED LEFT ENGINE SOUNDED ROUGH AND DECIDED TO RETUN TO THE AIRPORT AS PRECAUTION. UPON EXAMINATION (N903GD)
- [SDR 2025FA0000428](https://openairdocs.org/sdr/2025FA0000428), Jun 26, 2025: Beech A36. SPARK PLUG. BROKEN. NR 4 EGT WAS NOTED TO BE HIGHER THAN BASELINE AND THE ENGINE WAS RUNNING ROUGH. MECHANIC REMOVED THE #4 PLUGS AND FOUND  (N176X)
- [SDR NACA2025062200001](https://openairdocs.org/sdr/NACA2025062200001), Jun 22, 2025: Boeing 7673BG. IGNITER. INOPERATIVE. R ENG #1 IGNITOR INOP. REMOVED AND REPLACED RH IGNITOR PLUG IAW AMM 74-21-02 OPS CHECK OK IAW 74-00-00 (N563NC)
- [SDR I5PA2025062219301](https://openairdocs.org/sdr/I5PA2025062219301), Jun 19, 2025: Boeing 757223. IGNITER. WORN. FLT NT: MGE 410. RT ENG ABORT START QRH PERFORMED. R & R RT ENG #1 AND #2 IGNITER PLUGS PER AMM 74-21-01. OPS TEST OK PE (N193AN)
- [SDR NACA2025061800001](https://openairdocs.org/sdr/NACA2025061800001), Jun 18, 2025: Boeing 7673BG. IGNITER. NO TEST. #2 ENGINE #1 IGNITOR FAILED OPS CHECK. REMOVED AND REPLACED #2 ENGINE #1 IGNITOR PLUG IAW AMM 74-21-02 (N565NC)
- [SDR HALA20250606163](https://openairdocs.org/sdr/HALA20250606163), Jun 5, 2025: Airbus A321271N. IGNITER. FAILED. ETOPS - ENG 2 IGN A FAULT DURING START. REMOVED AND REPLACED IGN A IGNITER PLUG ON ENG 2 PER AMM 74-21-01. OPS CHECK GOO (N208HA)
- [SDR YENA2025060400565](https://openairdocs.org/sdr/YENA2025060400565), Jun 4, 2025: Airbus A321271NX. IGNITER. FAILED. FLT#2261, BOS-MAD. (ETOPS) .'ENG2 IGN B FAULT DURING ENG 2 START (ENG STARTED NORMALLY AFTERWARDS) ( IGNITION SYSTEMS B) (N4076J)
- [SDR SWAA2025060277156](https://openairdocs.org/sdr/SWAA2025060277156), May 31, 2025: Boeing 7377H4. EXCITER. INOPERATIVE. ABORTED ENGINE START #1 DUE TO NO LIGHT OFF ON THIRD ATTEMPT; CABIN CREW (F.O.) NOTED FIREBALL AND SMOKE IN TAILPIPE INS (N462WN)
- [SDR SWAA2025060277298](https://openairdocs.org/sdr/SWAA2025060277298), May 31, 2025: Boeing 7377H4. IGNITION LEAD. INOPERATIVE. ABORTED ENGINE START #1 DUE TO NO LIGHT OFF ON THIRD ATTEMPT; CABIN CREW (F.O.) NOTED FIREBALL AND SMOKE IN TAILPIPE INS (N462WN)
- [SDR SWAA2025060276616](https://openairdocs.org/sdr/SWAA2025060276616), May 31, 2025: Boeing 7377H4. PLUG. INOPERATIVE. ABORTED ENGINE START #1 DUE TO NO LIGHT OFF ON THIRD ATTEMPT; CABIN CREW (F.O.) NOTED FIREBALL AND SMOKE IN TAILPIPE INS (N462WN)
- [SDR HALA20250514133](https://openairdocs.org/sdr/HALA20250514133), May 13, 2025: Airbus A321271N. IGNITER. FAULTED. ETOPS - ON START ENG 2, ENGINE REATTEMPT 2ND ATTEMPT SUCCESSFUL ENG 2 IGN A FAULT. REPLACED #2 ENG A IGNITER PLUG PER AM (N214HA)
- [SDR 2025FA0000276](https://openairdocs.org/sdr/2025FA0000276), Apr 17, 2025: IGNITER. MALFUNCTIONED. INFORMED US THAT AN UNATTACHED IGNITOR HAD BEEN DISCOVERED IN THE ENGINE COMPARTMENT OF HIS AIRCRAFT, WHICH HAD LAST BEE (N509JJ)
- [SDR HALA20250409104](https://openairdocs.org/sdr/HALA20250409104), Apr 8, 2025: Airbus A321271N. IGNITER. DAMAGED. ETOPS - DURING ENG 1 BORESCOPE INSP OF THE COMBUSTION CHAMBER AND HPT NOZZLE GUIDE VANES, IGNITER PLUG WAS REMOVED AND F (N214HA)
- [SDR NACA2025032800001](https://openairdocs.org/sdr/NACA2025032800001), Mar 28, 2025: Boeing 76733A. IGNITER. FAULTED. REMOVED AND REPLACED RIGHT ENG #2 IGNITER PLUG AND #2 IGNITION EXCITER OPS CHECK GOOD. (N567NC)
- [SDR HALA20250317081](https://openairdocs.org/sdr/HALA20250317081), Mar 16, 2025: Airbus A321271N. IGNITER. DAMAGED. ETOPS - DURING #2 COMBUSTION LINER INSPECTION FOUND LOWER IGNTITOR PLUG DAMAGED. REMOVED AND REPLACED RIGHT HAND LOWER I (N228HA)
- [SDR CALA2025030302564](https://openairdocs.org/sdr/CALA2025030302564), Mar 3, 2025: Boeing 737924ER. IGNITER. FAILED. ABORTED START OF NUM 2 ENG WHEN FF DROPPED TO 0. FUEL SMELL IN C OCKPIT FUEL OBSERVED LEAKING #2 ENGINE LEFT IGNITION SY (N45440)
- [SDR YENA2025011000038](https://openairdocs.org/sdr/YENA2025011000038), Jan 10, 2025: Airbus A321271NX. IGNITER. FAILED. FLT#20, LHR-JFK. (ETOPS) 'ENG 1 IGN B FAULT ( IGNITION SYSTEMS B) SYSTEM B ); REMOVED AND REPLACED ENG 1 IGNITOR B REF A (N4077J)
- [SDR NACA2024111300001](https://openairdocs.org/sdr/NACA2024111300001), Nov 13, 2024: Boeing 7673BG. IGNITER. FAILED. LEFT ENGINE 2 FAILED START ATTEMPTS WITH #1 STARTER SELECTED. DEFERRED PER MEL 74-00-01B CAT C. REMOVED AND REPLACED LH  (N566NC)

All 703: https://openairdocs.org/jasc/7421/reports.md

## Airworthiness concern sheets (1)

- [AIR750-2026-07-X-7421-ACS](https://openairdocs.org/acs/AIR750-2026-07-X-7421-ACS): Cracking of Tempest Spark Plugs at Hot lock Assembly. Issued Aug 14, 2026

## Other codes in chapter 74

- [JASC 7400](https://openairdocs.org/jasc/7400): Ignition System (249 reports)
- [JASC 7410](https://openairdocs.org/jasc/7410): Ignition Power Supply (89 reports)
- [JASC 7411](https://openairdocs.org/jasc/7411): Low Tension Coil (14 reports)
- [JASC 7412](https://openairdocs.org/jasc/7412): Exciter (300 reports)
- [JASC 7413](https://openairdocs.org/jasc/7413): Induction Vibrator (5 reports)
- [JASC 7414](https://openairdocs.org/jasc/7414): Magneto/Distributor (2,447 reports)
- [JASC 7420](https://openairdocs.org/jasc/7420): Ignition Harness (Distribution) (213 reports)
- [JASC 7430](https://openairdocs.org/jasc/7430): Ignition Switching (111 reports)
- [JASC 7497](https://openairdocs.org/jasc/7497): Ignition System Wiring (97 reports)

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