Engine
The engine and everything bolted to it: ignition, fuel metering, exhaust, oil and turbochargers. Engine problems are the biggest single group in both the failure reports and the FAA's orders.
Operators and repair shops have filed 114,648 failure reports about this system since 1995, 29,291 of them in the last ten years. The part most often named in the reports is the engine. Among model families, the Boeing 737 appears most often in the last ten years; taking fleet size into account, the Boeing 767 has the highest rate among sizeable fleets, about 88.0 reports a year for every 100 aircraft.
Failure reports by year as filed with the FAA
Models most often named last ten years
Highest rate, fleets of 500 or more reports a year per 100 aircraft registered
Parts most often named
What was wrong with them the condition reported
Where in the system the FAA's codes
FAA orders 0 airworthiness directives · newest first
Who makes and modifies it
Engine series most often named last ten years
Sources: FAA service difficulty reports (yearly files since 1995, grouped by the FAA's four-digit system code into this site's fourteen systems), airworthiness directives, supplemental type certificates, technical standard order authorisations and special conditions from the FAA's Dynamic Regulatory System. Rates per 100 aircraft use today's register as the fleet; they show reporting as much as reliability, and commercial fleets report more. Connections as data: /graph/system/engine.json.