If you've ever looked up an aircraft on AeroPlanet's free Aircraft Research tool and seen "No FAA Service Difficulty Reports found," it's natural to wonder whether that means the aircraft has a clean maintenance history — or whether the data is just missing. We pulled the numbers across our entire aircraft database to find out, broken down by engine type.
The coverage gap, by engine type
"Coverage" here means the share of aircraft in our database that have at least one matched FAA Service Difficulty Report (SDR) on file. Here's what it looks like across roughly 316,000 aircraft:
| Engine type | Total aircraft | With an SDR on file | Coverage |
|---|---|---|---|
| Turbofan | 27,286 | 12,705 | 46.56% |
| Turboshaft | 9,780 | 2,337 | 23.90% |
| Turboprop | 14,084 | 2,869 | 20.37% |
| Turbojet | 1,804 | 424 | 23.50% |
| Reciprocating (piston) | 210,528 | 14,366 | 6.82% |
| Electric | 17,349 | 667 | 3.84% |
| None (gliders, balloons) | 9,149 | 275 | 3.01% |
| Other | 26,632 | 1,232 | 4.63% |
Every turbine class — turbofan, turboprop, turboshaft, turbojet — shows somewhere between 3x and 7x the SDR coverage of piston aircraft. Turbofans specifically show nearly seven times the coverage of piston singles and twins.
Why the gap exists — it's a paperwork requirement, not a safety signal
The FAA requires an SDR to be filed by specific categories of operator: type/design-certificate holders, Part 145 repair stations, and Part 121/135 air carriers and commercial operators. There is no equivalent legal requirement for a privately owned, individually operated aircraft flown under Part 91 — the category the overwhelming majority of piston GA aircraft fall into.
Turbofan aircraft skew heavily toward commercial (Part 121/135) operation — airline and charter fleets, exactly the operators required to file. Piston singles and twins skew heavily toward private ownership — exactly the operators who aren't. The coverage numbers above track that split almost exactly, which is what you'd expect if the requirement, not the aircraft's actual reliability, is driving the difference.
What this means if you're researching an aircraft
A privately-owned piston aircraft showing zero SDRs on Aircraft Research is the expected, normal result — not a red flag, and not evidence the aircraft has never had a mechanical issue. Conversely, if you're looking at a turbine aircraft with SDRs on file, that's also normal — it reflects that its operator was required to report, not that the aircraft is unusually troubled. Either way, an SDR count is one data point, not the whole picture: pair it with the aircraft's NTSB accident/incident history and its FAA registration status, both on the same lookup page.
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