CA.IX.F.K5FAA-S-ACS-7B · Nov 2023Knowledge
Importance of drag reduction, including propeller feathering, gear and flap retraction,...
Importance of drag reduction, including propeller feathering, gear and flap retraction, the manufacturer’s recommended control input and its relation to zero sideslip.
Bottom line
Drag from a windmilling propeller, extended landing gear, flaps extended beyond optimum, or any sideslip will reduce or even eliminate any modest single-engine performance that may exist. After the flaps and landing gear have been retracted and the propeller of the inoperative engine feathered, a key element in extracting best climb performance is minimizing sideslip.
Key numbers
| Number | What it means |
|---|---|
| One-third to one-half of a ball width from center toward the operative engine | Zero-slip ball |
| Approximately 2 to 3 degrees of bank with the ball slightly displaced toward the operative engine, for best climb performance at Vyse | Zero-slip at Vyse |
FAA references
- FAA-P-8740-66, Flying Light Twins Safely — FAA-P-8740-66
- AFH ch. 13 (pp. 13-29–13-30) — FAA-H-8083-3C
- AFH ch. 13 (p. 13-36) — FAA-H-8083-3C
- PHAK ch. 2 (p. 2-20) — FAA-H-8083-25C (2023)
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