Flow Divider Replacement Effects
November 19, 2025 sign-off · KBVS · Overhauled divider P/N 2576624-1
After the November work, idle EGTs moved closer together, while idle CHTs spread farther apart. Takeoff power indications were essentially unchanged.
Warm idle after landing
EGT · C2, C4 and C1 cooled most
CHT · C3 became hotter; C6 became cooler
Each flight has equal weight. These are recorded before/after differences; RPM, mixture and cooling conditions were not held identical.
Idle: lower RPM, higher fuel flow
Same taxi periods as the temperature charts.
| Measurement | Before | After |
|---|---|---|
| RPM | 928 | 862 |
| Fuel flow · GPH | 2.21 | 2.52 |
| MAP · inHg | 14.22 | 14.98 |
Takeoff: indications unchanged
17 flights before · 5 after · Nov 20–24 after the visit.
| Measurement | Before | After |
|---|---|---|
| RPM | 2,460 | 2,463 |
| Fuel flow · GPH | 37.17 | 37.14 |
| MAP · inHg | 39.26 | 39.25 |
What this shows about the divider
The strongest changes are at idle. The divider controls distribution at low fuel flow; as flow rises and its valve opens fully, the nozzles determine distribution. The observed pattern is consistent with that behavior. Precision operating manual, §1-11.
Injector/screen cleaning, C2/C4 intake-gasket replacement and a fuel-selector replacement accompanied the divider work. Their effects cannot be separated here. CHTs also reflect prior flight and cooling history; comparable intermediate-power data are sparse.
Source recordings, measurements and method
Non-overlapping stable 30-second ground windows after each recording’s last airborne sample (IAS >55 kt and groundspeed >35 kt). Filters: 800–1,000 RPM, oil 150–205°F, OAT 5–16°C, pressure altitude −700 to 1,200 ft. Maintenance ground runs are excluded. Window stability criteria.
Take the median of selected windows within each recording, then the median across recordings. Temperature spread is calculated within each window before aggregation, so it need not equal the difference between the plotted cylinder medians. Takeoff values use the existing departure intervals: MAP >35 inHg, RPM >2,350 and positive fuel flow. All dates above are local to the aircraft; source timestamps are UTC.
Before · 9 flights, 15 windows: 2025-10-22 / 349 · 2025-10-22 / 350 · 2025-10-26 / 351 · 2025-10-27 / 354 · 2025-10-29 / 355 · 2025-11-02 / 357 · 2025-11-08 / 360 · 2025-11-09 / 365 · 2025-11-10 / 369
After · 3 flights, 17 windows: 2025-11-21 / 376 · 2025-11-24 / 380 · 2025-11-24 / 381
Idle recording medians · CSV · Selected idle windows · CSV · Takeoff comparison · CSV