# JASC 7714: Engine RPM Indicating System

- Type: JASC system/component code (FAA)
- ATA chapter: 77 Engine Indicating
- Title in the code table: ENGINE RPM INDICATING SYSTEM
- Service difficulty reports: 1,357
- FAA code table: https://www.faa.gov/sites/faa.gov/files/JASC_Code.pdf#page=66
- Page: https://openairdocs.org/jasc/7714

## What it covers

The system including the indicator and sensor which indicates engine speed in revolutions per minute (RPM). Typical parts are, cable, connector, tachometer, tachometer generator, N1 indicator.

## Service difficulty reports (1,357, newest 50)

- [SDR QR9R2026082100001](https://openairdocs.org/sdr/QR9R2026082100001), Aug 21, 2026: Bolkms BK117C2. SENSOR. FAILED. IN FLIGHT NR NEEDLE ON TRIPLE TAC FAILED. IN FLIGHT NR FLUCTUATED CONTINUOUSLY BETWEEN NORMAL RANGE AND 0 WITH ASSOCIATE
- [SDR QR9R2026081100001](https://openairdocs.org/sdr/QR9R2026081100001), Aug 11, 2026: Bolkms BK117C2. SENSOR. FAILED. OVSP SYSTEM 1 FAILED DURING START RUN-UP. MAINTENANCE ARRIVED AND PULLED CB AND CAUTION LIGHT WAS STILL ILLUMINATED AFTE
- [SDR DALA2026080704581](https://openairdocs.org/sdr/DALA2026080704581), Aug 7, 2026: Airbus BD5001A10. PRESSURE SENSOR. FAULTED. DIVERTED TO DTW DUE TO RIGHT ENGINE FAULT WITH ASSOCIATED N1 ERRATIC AND N1 DROP. REPLACED BURNER PRESSURE SENSOR PER A2 (N120DU)
- [SDR QR9R2026073000001](https://openairdocs.org/sdr/QR9R2026073000001), Jul 30, 2026: Bolkms BK117C2. SENSOR. FAULTY. ON TAKEOFF, ROTOR RPM WARNING LIGHT AND NRO NEEDLE ON TRIPLE TACH WENT TO ZERO. REMOVED AND REPLACED ROTOR RPM SENSOR IA
- [SDR QMLA2026072520049](https://openairdocs.org/sdr/QMLA2026072520049), Jul 23, 2026: Bell 407. DUAL TACHOMETER. DEGRADED. NEEDLES ON DUAL TACH NOT ALIGNED WHILE RUNNING. FADEC DEGRADED/RESTART FAULT LIGHT ILLUMINATED AFTER STARTUP. REMOVED AN (N404LL)
- [SDR QR9R2026071500001](https://openairdocs.org/sdr/QR9R2026071500001), Jul 15, 2026: Bolkms BK117C2. SENSOR. FAILED. OVERSPEED CAUTION LIGHT ILLUMINATED DURING START RUN-UP. REMOVED AND REPLACED #2 ENGINE OVERSPEED SENSOR IAW EMM 77-14-0
- [SDR UIEA2026060900455](https://openairdocs.org/sdr/UIEA2026060900455), Jun 9, 2026: Boeing 767375. CIRCUIT CARD. FAULTED. RAT DEPLOYED RIGHT AFTER ROTATION ON TAKE-OFF. GREEN PRESSURE LIGHT ILLUMINATED(<P>REMOVED AND REPLACED LH ENG SPEED CAR (N649GT)
- [SDR QR9R2026051300001](https://openairdocs.org/sdr/QR9R2026051300001), May 13, 2026: Bolkms BK117C2. SENSOR. OUT OF TOLERANCE. ENG 1 OVERSPEED ON CAD. PULLING THE BREAKER MADE IT GO AWAY, PUTTING THE BREAKER BACK IN MADE IT COME BACK ON. WHEN GOIN
- [SDR CALA2026041715440](https://openairdocs.org/sdr/CALA2026041715440), Apr 15, 2026: Boeing 767424ER. SENSOR. FAULTED. RIGHT ENG ANALOG N2 STATUS MSG DISPLAYED DEBRIEFED CREW. CREW STATED AFTER TAKE OFF INTO CRUISE THEY NOTICED RIGHT ENG B (N67052)
- [SDR QR9R2026032400002](https://openairdocs.org/sdr/QR9R2026032400002), Mar 24, 2026: Bolkms BK117C2. SENSOR. FAILED. #1 OVSP FAIL CAUTION ILLUMINATED AFTER RUN-UP. REMOVED AND REPLACED #1 ENG OVERSPEED SENSOR IAW EMM 77-14-00-900-802-A01
- [SDR 2026FA0000186](https://openairdocs.org/sdr/2026FA0000186), Mar 11, 2026: Piper PA44180. QUICK DISCONNECT. DEFECTIVE. WHILE IN FLIGHT THE LEFT ENGINE RPM READING BECAME ERRATIC, GOING FROM NORMAL TO PAST RED LINE QUICKLY BACK AND FORTH. P (N8024Q)
- [SDR QMLA2026012720006](https://openairdocs.org/sdr/QMLA2026012720006), Jan 27, 2026: Bolkms BK117C2. SENSOR. INOPERATIVE. NUMBER 2 ENGINE OVSP FAIL DID NOT EXTINGUISH. (N984ME)
- [SDR QR9R2026011300001](https://openairdocs.org/sdr/QR9R2026011300001), Jan 13, 2026: Bolkms BK117C2. SENSOR. FAILED. #2 ENGINE OVERSPEED FAIL LIGHT CAME ON AT 0.2 HRS AT HOVER. A TEST FLIGHT EVAL FOUND #2 ENGINE OVERSPEED FAIL CAUTION LI
- [SDR QR9R2025092400001](https://openairdocs.org/sdr/QR9R2025092400001), Sep 24, 2025: Bolkms BK117C2. SENSOR. FAILED. OVSP ON #1 ENGINE WOULD NOT GO OUT AFTER STARTING ENGINE. REMOVED AND REPLACED OVERSPEED SENSOR IAW 77-14-00-900-802. T/
- [SDR QR9R2025080100001](https://openairdocs.org/sdr/QR9R2025080100001), Aug 1, 2025: Bolkms BK117C2. SENSOR. FAILED. #2 OVERSPEED FAIL CAUTION REPEATEDLY APPEARED DURING HOVER AND AT FLIGHT. REMOVED AND REPLACED #2 ENG OVERSPEED SENSOR I
- [SDR QR9R2025072400002](https://openairdocs.org/sdr/QR9R2025072400002), Jul 24, 2025: Bolkms BK117C2. SENSOR. FAILED. OVERSPEED FAIL CAUTION ON #2 ENG CAME ON APPROXIMATELY 1 MINUTE AFTER START. DURING TROUBLESHOOTING, FOUND PINS 4 AND 5 
- [SDR QR9R2025072300002](https://openairdocs.org/sdr/QR9R2025072300002), Jul 23, 2025: Bolkms BK117C2. SENSOR. FAILED. ENG 1 OVSP FAIL CAUTION DURING HOVER TAXI. REMOVED AND REPLACED #1 ENGINE OVERSPEED SENSOR. COMPLETED OVERSPEED TEST IAW
- [SDR 8HBR20250721071](https://openairdocs.org/sdr/8HBR20250721071), Jul 13, 2025: Cessna. SHAFT. DEFECTIVE. TACHOMETER CABLE ORDERED NEW FROM TEXTRON, PN: S2550-12, RECEIVED WITH METAL END OF TACHOMETER SHAFT THAT CONNECTS TO TH
- [SDR CALA2025070306203](https://openairdocs.org/sdr/CALA2025070306203), Jun 30, 2025: Boeing 757224. SENSOR. FAULTED. AFTER TAKEOFF DURING INITIAL CLIMBS THE LEFT BLEED OFF LIGHT AND ASSOCIATED PACK OFF LIGHT ILLUMINATED. WE FOLLOWED THE  (N57111)
- [SDR VGCA20250513001](https://openairdocs.org/sdr/VGCA20250513001), May 13, 2025: Cvac STC3405800. TACH GENERATOR. STRIPPED. RIGHT ENGINE RPM SPOOLED DOWN IN FLIGHT. ENGINE WAS SHUTDOWN. SUBSEQUENT INSPECTION FOUND THAT TACH GENERATOR DRIVE SHAF (N391FL)
- [SDR QR9R2025050900001](https://openairdocs.org/sdr/QR9R2025050900001), May 9, 2025: Bolkms BK117C2. SENSOR. FAILED. #1 ENGINE OVERSPEED FAIL CAUTION CAME ON IN FLIGHT. DURING TROUBLESHOOTING, FOUND OVERSPEED SENSOR BAD. FAILS TESTS IN E
- [SDR 37CA2025/02/2601](https://openairdocs.org/sdr/37CA2025%2F02%2F2601), Feb 20, 2025: Agusta AW119MKII. TACH GENERATOR. DEFECTIVE. N1 TACHOMETER GENERATOR ERRATIC READINGS DURING START UP CAUSING A MIS-COMPARE P CAUTION MESSAGE. (N354LL)
- [SDR CALA2025021302309](https://openairdocs.org/sdr/CALA2025021302309), Feb 9, 2025: Boeing 75733N. TACHOMETER. FAULTED. N1 OVERSPEED INDICATION NUMBER 2 ENGINE N1 OVERSPEED BEGAN DURING CLIMB AT 15,000FT . DURING APPROACH BACK EPR WENT BLAN (N57869)
- [SDR QR9R2025011700002](https://openairdocs.org/sdr/QR9R2025011700002), Jan 17, 2025: Bolkms BK117C2. SENSOR. FAILED. #2 OVSP FAIL CAUTION ILLUMINATED AND WOULD NOT EXTINGUISH WITH AVIONICS RESETTING CB OR DOING HARD RESET. REMOVED AND RE
- [SDR QR9R2025011500001](https://openairdocs.org/sdr/QR9R2025011500001), Jan 15, 2025: Bolkms BK117C2. SENSOR. INTERMITTENT. #2 ENG OVSP FAIL LIGHT ILLUMINATED IN FLIGHT. A MAINTENANCE TEST FLIGHT VERIFIED #2 ENG OVSP FAIL LIGHT WAS INTERMITTENT
- [SDR ABXA20241229274](https://openairdocs.org/sdr/ABXA20241229274), Dec 29, 2024: Boeing 767328. CIRCUIT CARD. MALFUNCTIONED. AFTER PUSHBACK, STATUS MSG L ENG SPEED CARD AC RETURNED TO GATE (BTB)AND MTX GROUNDED ACMTX PERFORMED STATUS MSG ERASE P (N1499A)
- [SDR QR9R2024111400002](https://openairdocs.org/sdr/QR9R2024111400002), Nov 14, 2024: Bolkms BK117C2. SENSOR. FAULTED. DURING FLIGHT, #1 ENG OVERSPEED FAILURE CAUTION ILLUMINATED ON THE CAD AND WOULD NOT GO OUT. DURING TROUBLESHOOTING, FOU
- [SDR QR9R2024101800001](https://openairdocs.org/sdr/QR9R2024101800001), Oct 18, 2024: Bolkms BK117C2. SENSOR. FAILED. OVSP FAIL LIGHT DID NOT EXTINGUISH UPON STARTING. REMOVED AND REPLACED #2 ENGINE OVERSPEED SENSOR IAW EMM 77-14-00-900-8
- [SDR QR9R2024101000002](https://openairdocs.org/sdr/QR9R2024101000002), Oct 10, 2024: Bolkms BK117C2. SENSOR. FAULTED. IN FLIGHT, #2 ENGINE OVERSPEED FAIL LIGHT ILLUMINATED. REMOVED AND REPLACED OVERSPEED SENSOR IAW ENG MANUAL 77-14-00-900
- [SDR QR9R2024091300004](https://openairdocs.org/sdr/QR9R2024091300004), Sep 13, 2024: Bolkms BK117C2. SENSOR. WARNING LIGHT. #2 OVSP FAIL CAUTION LIGHT ILLUMINATED DURING HOVER FLIGHT AND WAS ON AND OFF INTERMITTENTLY WITH BOTH TWIST GRIPS IN TH
- [SDR QR9R2024091300003](https://openairdocs.org/sdr/QR9R2024091300003), Sep 13, 2024: Bolkms BK117C2. SENSOR. FAILED. #1 ENG OVERSPEED FAIL CAME ON DURING HOVER TAXI. A TEST FLIGHT EVAL FOUND THAT AFTER 5 ATTEMPTS ON RESETTING #1 ENGINE O
- [SDR QR9R2024080900003](https://openairdocs.org/sdr/QR9R2024080900003), Aug 9, 2024: Bolkms BK117C2. INDICATOR. INOPERATIVE. DURING RUN-UP, NR INOP ON TRIPLE TACH. REMOVED AND REPLACED TRIPLE INDICATOR IAW AMM 62-41-00, 4-3. MOC SUCCESSFULLY COM
- [SDR QR9R2024080800001](https://openairdocs.org/sdr/QR9R2024080800001), Aug 8, 2024: Bolkms BK117C2. TACHOMETER. FLUCTUATES. N2 NEEDLE #2 ENGINE KEEPS FLUCTUATING BETWEEN 0 AND FLIGHT DURING FLIGHT. REMOVED AND REPLACED TRIPLE INDICATOR RPM; MOC
- [SDR CALA2024080700383](https://openairdocs.org/sdr/CALA2024080700383), Aug 5, 2024: Boeing 757224. SENSOR. FAULTY. INFLIGHT RT ENGINE BLEED OFF. RT CTR FUEL PUMP INOP. RT ENGINE N3 INDICATING 0 REMOVED AND REPLACED E2 TACHOMETER REF 77 (N17139)
- [SDR NACA2024080400001](https://openairdocs.org/sdr/NACA2024080400001), Aug 4, 2024: Boeing 7673BG. CIRCUIT CARD. FAILED. L ENGINE SPEED CARD. REMOVED AND REPLACED LEFT ENGINE SPEED CARD IAW AMM 77-12-01 TEST REPORTED OK (N566NC)
- [SDR FDEA202407251050](https://openairdocs.org/sdr/FDEA202407251050), Jul 25, 2024: Boeing 7572G5. TACH GENERATOR. FAILED. AFTER TAKEOFF, RECEIVED L ENG BLEED OFF EICAS RAN QRH 2.1.14 LEVELED AT FL360. NOTICED CABIN ALT AT 8000 WHILE 5 MIN CAB (N944FD)
- [SDR ABXA20240619120](https://openairdocs.org/sdr/ABXA20240619120), Jun 19, 2024: Boeing 767338. SENSOR. MALFUNCTIONED. LEFT ENG SPEED CARD MESSAGE DURING TAXI. AC RETUREND TO GATE MAINTENANCE GROUNDED AC AND RANG OUT N2 SPEED SENSOR IAW WD (N390CM)
- [SDR CALA2024030800663](https://openairdocs.org/sdr/CALA2024030800663), Mar 5, 2024: Boeing 737924. SENSOR. FAULTY. CLIMBING THROUGH 13000 FELT SHARP BUMP THEN VIBE IN AIRFRAME..EGT SPIKED AND N1 ROLLBACK INCREASED NORMALLY, HOWEVER, NO (N31412)
- [SDR QR9R2024022000002](https://openairdocs.org/sdr/QR9R2024022000002), Feb 20, 2024: Bolkms BK117C2. TACHOMETER. FAILED. UPON STARTING #1 ENGINE, ROTOR RPM NEEDLE MOVED UP TO APPROXIMATELY 97% AND STUCK IN THAT POSITION. N2 AND ROTOR RPM NEE
- [SDR QR9R2023102300001](https://openairdocs.org/sdr/QR9R2023102300001), Oct 23, 2023: Bolkms BK117C2. TACHOMETER. FAILED. TRIPLE TACH WENT TO ZERO DURING FLIGHT. ALL OTHER INDICATIONS HAD RTR AND N2S WITHIN THE NORMAL OPERATING RANGE. REMOVED
- [SDR YV3R2023051000565](https://openairdocs.org/sdr/YV3R2023051000565), Apr 26, 2023: Robsin R22BETAII. CONTROLLER. DEFECTIVE. CUSTOMER REPORTED GOVERNOR CONTROLLER ASSEMBLY P/N: B286-2 WAS DEFECTIVE.
- [SDR YV3R2023042700563](https://openairdocs.org/sdr/YV3R2023042700563), Apr 20, 2023: Robsin R44RAVENII. CONTROLLER. DEFECTIVE. CUSTOMER REPORTED CONTROLLER ASSEMBLY P/N: D278-2 OVER SPEEDS ENGINE AND ROTOR SYSTEM. (N276RC)
- [SDR DALA2023041803076](https://openairdocs.org/sdr/DALA2023041803076), Apr 15, 2023: Boeing 757231. UNKNOWN. UNKNOWN. SHIP 6811 - ATB - RETURNED TO JFK DUE TO RIGHT BLEED OFF WITH ASSOCIATED RIGHT PACK OFF MESSAGE. ALSO HAD RIGHT CENTER F (N705TW)
- [SDR YV3R2023031400551](https://openairdocs.org/sdr/YV3R2023031400551), Jan 4, 2023: Robsin R44RAVENII. CONTROLLER. DEFECTIVE. CUSTOMER REPORTED CONTROLLER ASSEMBLY P/N: D278-2 GIVING A HIGH READING OF MORE THAN 101% RPM.
- [SDR YV3R2023031400549](https://openairdocs.org/sdr/YV3R2023031400549), Dec 15, 2022: Robsin R44RAVENII. CONTROLLER. MALFUNCTIONED. CUSTOMER REPORTED CONTROLLER ASSEMBLY P/N: D278-2 MALFUNCTIONED.
- [SDR 2022F00516](https://openairdocs.org/sdr/2022F00516), Dec 13, 2022: Cessna 340CESSNA. TACH GENERATOR. SEIZED. THE LH TACH GENERATOR SEIZED INTERNALLY CAUSING THE LH TACHOMETER INDICATION TO FALL TO ZERO. (N157SG)
- [SDR HALA2022121300309](https://openairdocs.org/sdr/HALA2022121300309), Dec 12, 2022: Airbus A321271N. SENSOR. FAULTED. ECAM IN AIR "ENG 2 FADEC SYS FAULT" PER FPR ENG 2B-0452-N2 SPEED SENSOR FAIL. PERFORMED T/S IAWTSM 77-11-00-810-812-A. D (N214HA)
- [SDR QR9R2022120800001](https://openairdocs.org/sdr/QR9R2022120800001), Dec 8, 2022: Bolkms BK117C2. TACHOMETER. FAULTY. ABORTED TAKE-OFF DUE TO ROTOR TACH FAILURE. ROTOR NEEDLE DID NOT MOVE ON FIRST ENGINE START. UPON TROUBLESHOOTING, NR SP
- [SDR QR9R20220912001](https://openairdocs.org/sdr/QR9R20220912001), Sep 12, 2022: Bolkms BK117C2. SENSOR. FAULTED. #2 OVERSPEED FAIL CAUTION ILLUMINATED DURING RUN-UP. REMOVED AND REPLACED ENG #2 OVERSPEED SENSOR I/A/W 77-14-00-900-802
- [SDR QR9R20220831003](https://openairdocs.org/sdr/QR9R20220831003), Aug 31, 2022: Bolkms BK117C2. NONE. ILLUMINATED. OVERSPEED FAIL LIGHT ILLUMINATED DURING FLIGHT ON #2 ENGINE. DURING LANDING, #2 ENGINE OIL PRESSURE VACILLATED BETWEEN 0

All 1,357: https://openairdocs.org/jasc/7714/reports.md

## Other codes in chapter 77

- [JASC 7700](https://openairdocs.org/jasc/7700): Engine Indicating System (705 reports)
- [JASC 7710](https://openairdocs.org/jasc/7710): Power Indicating System (191 reports)
- [JASC 7711](https://openairdocs.org/jasc/7711): Engine Pressure Ratio (EPR) (456 reports)
- [JASC 7712](https://openairdocs.org/jasc/7712): Engine BMEP/Torque Indicating (1,239 reports)
- [JASC 7713](https://openairdocs.org/jasc/7713): Manifold Pressure (MP) Indicating (77 reports)
- [JASC 7720](https://openairdocs.org/jasc/7720): Engine Temperature Indicating System (695 reports)
- [JASC 7721](https://openairdocs.org/jasc/7721): Cylinder Head Temperature (CHT) Indicating System (62 reports)
- [JASC 7722](https://openairdocs.org/jasc/7722): Engine EGT/TIT Indicating System (1,198 reports)
- [JASC 7730](https://openairdocs.org/jasc/7730): Engine Ignition Analyzer System (52 reports)
- [JASC 7731](https://openairdocs.org/jasc/7731): Engine Ignition Analyzer (15 reports)
- [JASC 7732](https://openairdocs.org/jasc/7732): Engine Vibration Analyzer (237 reports)
- [JASC 7740](https://openairdocs.org/jasc/7740): Engine Integrated Instrument System (53 reports)
- [JASC 7797](https://openairdocs.org/jasc/7797): Engine Indicating System Wiring (592 reports)

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