Centaurus,
Some modern aircraft such as B350 have the gear horn silence button mounted on the left power lever knob. With flaps UP or APPROACH and gear UP the horn will sound below 85%N1 but may be silenced. Once the flap lever is mover towards LAND (there are no intermediate positions) the horn cannot be silenced regardless of throttle setting. Although the aircraft is an excellent performer on one engine, selecting full flap unless landing is assured or unless the aircraft is on a stabilised approach, may require considerable power from the live engine to achieve the aim point! An easy trap for a VMCA type scenario.
All our pilots use the horn silence switch to stop the passengers getting jumpy. And this means every power reduction from FL350 down. Naturally with an adjustment every few thousand feet it becomes second nature so other disciplines are incorporated into SOP’s to ensure the landing gear is always down for the landing!
The method used is to always select gear down just prior to turning base (or one dot below glide path on ILS). The increased drag is offset by the descent and no power change should be necessary. As a check, descent below circuit height is not commenced without three greens. Bearing this in mind the pilot may only need two power settings for entering downwind, one for two engines and a slightly higher setting for one engine. Both settings will achieve 120 KIAS subject to weight. Flaps are selected to approach entering downwind. Vfe – 202 KIAS and Vlo – 184 KIAS so they act like speed brakes to achieve gear speed. By setting the power, airspeed and rate of descent are monitored during base and finals. If either are outside the parameters then gear will probably be the culprit. Landing flaps are used in two engine ops as ‘appropriate’ or asymmetric ops at the minima to achieve Threshold Speed. The ‘appropriate’ position for normal ops is usually 400 – 500 feet. In either case power is reduced to idle at about 50 feet with touchdown on the 1000 ft markers.
The technique is highly disciplined and demonstrated during route checks and proficiency checks. It becomes second nature.
We used the technique many years ago when operating turbo-charged pistons. The gradual power reduction to touch-down followed by maximum use of the runway and backtracking allowed a good rundown of the turbo-chargers. We operated those aircraft over many thousands of hours without a problem.