Which part of the flight?
47–193 seconds at high power around each takeoff. These are medians from the takeoff roll and initial climb, near 39 inHg manifold pressure and 2,465 RPM. They are not trip averages, cruise fuel flow, or total fuel burned.
February–March 2025 · Fuel-flow study
The fuel-flow change, flight by flight.
The finding is lower fuel flow during takeoff and initial climb, at similar engine settings. The table identifies every departure; the map and graphs show the exact part of each flight we compared.
Earlier reference
37.30 GPH20 comparable departures · 1,347°F TIT
July–December 2024The low-flow period
26.67 GPH13 comparable departures · 1,586°F TIT
February 1–March 3, 2025Later comparison
36.82 GPH14 comparable departures · 1,340°F TIT
April 2025–February 2026What does “normal” mean here?
About 37 GPH was this airplane’s usual earlier pattern. Eighteen of 20 earlier comparable departures were 36.7–37.9 GPH; two were also low, at 24.6 and 25.4. All 20 contribute to the 37.30 GPH reference median. This describes recorded behavior, not an approved operating setting.
What changed?
All 13 comparable departures were below that usual pattern. Their median was 26.67 GPH, about 28.5% lower. TIT—exhaust temperature at the turbo—rose from 1,347°F to 1,586°F. The repeated combination is the concern; the logs do not identify whether pilot settings or a fuel-system change caused it.
The 13 comparable departures
These are the trips with lower takeoff fuel flow.
Each row is one departure from Centennial (KAPA) or Limon (KLIC). Fuel flow and TIT summarize only the selected takeoff/climb window. Select a route to see that window on the graph.
| Departure · UTC | Trip | Fuel during window | Vs. 37.30 GPH | Window | TIT |
|---|---|---|---|---|---|
| KAPA → KLIC ↗ | 32.25 GPH | 13.5% lower | 72 sec | 1,433°F | |
| KLIC → KAPA ↗ | 32.25 GPH | 13.5% lower | 47 sec | 1,422°F | |
| KAPA round-trip ↗ | 29.68 GPH | 20.4% lower | 56 sec | 1,471°F | |
| KAPA round-trip ↗ | 24.87 GPH | 33.3% lower | 56 sec | 1,615°F | |
| KAPA round-trip ↗ | 28.35 GPH | 24.0% lower | 59 sec | 1,526°F | |
| KAPA round-trip ↗ | 24.99 GPH | 33.0% lower | 76 sec | 1,628°F | |
| KAPA round-trip ↗ | 27.33 GPH | 26.7% lower | 88 sec | 1,586°F | |
| KAPA round-trip ↗ | 25.81 GPH | 30.8% lower | 130 sec | 1,640°F | |
| KAPA → KLIC ↗ | 25.19 GPH | 32.5% lower | 98 sec | 1,642°F | |
| KLIC → KAPA ↗ | 31.30 GPH | 16.1% lower | 135 sec | 1,495°F | |
| KAPA round-trip ↗ | 24.42 GPH | 34.5% lower | 49 sec | 1,638°F | |
| KAPA round-trip ↗ | 25.28 GPH | 32.2% lower | 193 sec | 1,654°F | |
| KAPA round-trip ↗ | 26.67 GPH | 28.5% lower | 49 sec | 1,560°F |
The March 1 flight at 01:07 UTC was February 28 at 6:07 p.m. Mountain time. A KAPA round-trip means a flight that returned to Centennial; it does not imply that it stayed in the traffic pattern.
The other three journeys
What about the March 1 Texas trip?
These departures miss the comparison’s power or altitude criteria. Excluded does not mean normal. Hereford → Dalhart also shows low fuel flow with high TIT and deserves separate review.
| Departure · UTC | Trip | Window readings | Why it is outside the 13-departure comparison |
|---|---|---|---|
| KAPA → KHRX ↗ | 32.54 GPH 1,391°F TIT | 37.19 inHg MAP is outside the 38–40 comparison range.Lower manifold pressure: this departure cannot be treated as the same-power comparison. | |
| KHRX → KDHT ↗ | 25.25 GPH 1,616°F TIT | 3,813.80 ft pressure altitude is outside the 5,200–7,500 comparison range.25.25 GPH with 1,616°F TIT resembles the low-flow / high-temperature pattern, but the lower altitude excludes it from the 13-departure comparison. | |
| KDHT → KAPA ↗ | 34.09 GPH 1,384°F TIT | 4,050.60 ft pressure altitude is outside the 5,200–7,500 comparison range.Lower departure altitude: shown for context, without a normal/abnormal verdict from this comparison. |
Follow the evidence
Where it happened. When it happened.
16 journeys, four airports, 14.8 recorded airborne hours. Gray lines show travel; amber highlights only the compared takeoff/climb seconds. The rest of a route is not labeled anomalous.
Select a departure in the table or a route on the map.
Recorded route · whole flightSelected routeCompared takeoff / initial-climb interval only
Inspect an individual departure.
Select a trip above. Its graph opens on takeoff and initial climb, with the measured window highlighted and earlier reference lines where the comparison applies.
Exactly what was compared
For each flight, search from 45 seconds before to three minutes after the first recorded IAS >55 kt and groundspeed >35 kt. This is an approximate departure reference, not a recorded wheels-off event. Retain high-power seconds with MAP >35 inHg and RPM >2,350, then calculate the median reading for each departure.
The 13 departures have window medians of 5,200–7,500 ft pressure altitude, 38–40 inHg MAP and 2,400–2,500 RPM. The earlier 20 and later 14 meet the same criteria. Selection does not depend on fuel flow being low. Short windows do not establish how long any difference persisted later in the climb or in cruise.
Read the lifetime finding · Download all 47 compared departures
How these routes were reconstructed
The February–March archive contains 17 flight-bearing logs, grouped into 16 journeys. Flight activity ends March 3; March 20 records ground activity only. Actual GPS tracks are sampled every five seconds; departure graphs use one-second samples. Gaps remain unconnected. Airport endpoints are inferred from low-speed GPS positions and OurAirports locations.
A March 2 recorder restart split one KAPA round-trip into two files. The second filename says CO93, but GPS shows the airplane already airborne. It is one journey, not a visit to CO93. All displayed dates/times are UTC.