PowerPac Spoilers “Jet Type” design is similar to those used on commercial jet airliners. The system consists of single flat plates, one on top of each wing that lies flat when not in use. When deployed, they extend upward into the slipstream at a 60-degree angle, thereby "spoiling" a portion of the lift being generated by the wing, while at the same time creating drag.
The operating system is hydraulic. All kits (except for the Aerostar) employ an electric-hydraulic pump or PowerPac to supply hydraulic pressure.
In the unlikely event of a leak, the drop in pressure affects deployment of each spoiler equally, eliminating for all practical purposes, the chances of asymmetrical deployment. Spoilers are deployed when the pilot pushes a "one-touch button" on the instrument panel.
When the Spoilers are fully deployed, i.e. 60 degrees up position, limit switches on each actuator close, shutting off hydraulic pressure, turning on an annunciator light in front of the pilot for each Spoiler, and applying power to a second hydraulic solenoid (fail-safe) valve. This valve traps hydraulic pressure in the Spoiler circuit lines keeping the Spoilers deployed until there is an interruption of electrical power.
If the pilot pushes the button a second time, or if power is removed from the fail-safe solenoid valve for any other reason, (such as an aircraft electrical system failure) the valve opens allowing hydraulic fluid to flow back into the reservoir. Aerodynamic pressure on the Spoiler panels, in addition to return springs, insures immediate retraction of the Spoilers as the hydraulic pressure dissipates.
Spoilers are equally useful and certified in icing conditions and may be deployed at any airspeed up to Vne.