Frequently Asked Questions:

Click on each question below to jump to the corresponding answer about our aftermarket airplane spoilers. If you have you have further questions you would like to have answered, please see our contact page or call us at 253-851-1769.


What is the Purpose of the Spoiler on an Airplane?
Why Aircraft Spoilers?
Why PowerPac Spoilers?
How Do PowerPac Aircraft Spoilers Work?
Have the PowerPac Spoilers been Thoroughly Tested?
Are the Spoilers made from Quality Components?


  • With PowerPac Spoilers you command descent rates up to 3.5 times faster!
  • Avoid engine shock cooling and maintain cabin pressure.
  • Plus you can deploy and retract PowerPac Spoilers in Icing Conditions.
  • When it’s time to come down you’ll be very glad you have PowerPac Spoilers.

What is the Purpose of the Spoiler on an Airplane?

The spoiler on an airplane allows the pilot to set a desired descent rate at any altitude without having to change the power setting, thereby eliminating any chance of engine damage caused by shock cooling the engine.   Deploying the airplane spoiler in level flight reduces excessive airspeed without making any major power change.  The spoiler aids the pilot in getting down fast and safely in extreme turbulence and icing conditions.


Why Aircraft Spoilers?

• The addition of aftermarket spoilers to your aircraft provides an additional dimension of control that will transform the manageability of your airplane's descent characteristics.

• Rapid descents may be made without having to reduce power, thereby maintaining engine temperatures at a comfortable level, and eliminating the risk of engine "shock cooling."

• Maintain normal cruise/descent speeds until much closer to the airport without worrying about how you'll slow to gear extension speed.

• Deploying Spoilers instead of reducing power and/or lowering the landing gear will safely accomplish rapid reduction in airspeed.

• Descend rapidly through icing conditions without risk of accumulating additional ice on extended landing gear surfaces.

• Reap the benefits of high altitude flight longer. Take advantage of tailwinds and smooth air until you are much closer to your destination before beginning your descent.

• Comply with ATC descent clearances or speed reduction requests with confidence. Eliminate the need for such awkward procedures as extending the landing gear … then having to retract it once the request has been met.


Why PowerPac Spoilers?

• Thoroughly tested and operational in icing conditions. This is especially beneficial when a descent is required through cloud layers in which significant ice accumulation has been reported. In many situations, the use of Spoilers will minimize the time spent in actual icing conditions.

• PowerPac Spoilers are true Spoilers. When deployed they function to reduce lift rather than merely increase drag. Lift induced loads carried by the wings are actually reduced during Spoiler deployment. Consequently, many pilots find it beneficial to use PowerPac Spoilers to slow the airplane when sudden unexpected turbulence is encountered.

• Hydraulic operation practically eliminates the chance of asymmetric deployment.

• Fail-safe design. Loss of electrical power for any reason causes the Spoilers to retract.

• No operating restrictions. Spoilers may be deployed in any configuration and at speeds up to Vne.

• High quality precision machined components. PowerPac Spoiler actuators and hydraulic pump parts are manufactured by computer programmed milling machines from solid aluminum billet alloy stock and hardened steel.

• The PowerPac Spoiler system takes up no room in any passenger or baggage areas (in most types, call for details).


How Do PowerPac Aircraft Spoilers Work.

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. The Aerostar design consists of a manifold that directs hydraulic pressure from the airplane system to the two wing actuators.

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. In addition, if a leak occurs in the Spoiler circuit of the Aerostar, an automatic timer signals a solenoid valve to close, isolating the Spoiler hydraulic circuit from the airplane's system.
Spoilers are deployed when the pilot pushes a "one-touch button" on the instrument panel. This applies power to the hydraulic pump or, on the Aerostar opens a valve on the manifold. In either case hydraulic pressure is applied to each Spoiler wing actuator.

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.


PowerPac Spoilers Have Been Thoroughly Tested.

Initial flight-testing of a variety of Spoiler plate sizes in various locations on the wings is performed before a design configuration is finalized. Target performance for the Spoilers is an increase in descent rate of between 50 and 100 percent of what it would be without them. Additional goals include minimizing "spoiler rumble" and pitch change during deployment.
Elaborate stall testing is undertaken with all possible combinations of gear position, flap position and CG range included. The purpose is to see that there is no diminution of control affectivity, no adverse change in stall characteristics and no substantial increase in stall speeds when the Spoilers are deployed.

Asymmetric deployment testing is performed to insure the airplane remains fully controllable in the highly unlikely event that one Spoiler fails to retract (or to deploy). Test flights are made with only one Spoiler deployed that includes high-speed dives, stalls, landings and go-arounds. Even in the worst-case situation (high-speed), less than 10 lbs of force on the yoke is required to maintain wings level.

High-speed test flights are made with Spoilers deployed at speeds up to Vd (design maximum dive speed). This speed is redline plus 10% and is allowable only for test purposes on an airplane specially licensed by the FAA in the experimental category. These flights are made to insure, among other things, that no unusual controllability problems or vibrations occur at higher indicated airspeeds.

FAA requirements to test for successful operation in icing weather were very difficult to accomplish. Repeated test flights in icing conditions failed to produce any accumulation anywhere close to the Spoilers. Consequently it was necessary to create an artificial ice accumulation on and around the Spoiler plates. With the Spoilers in the retracted position, wing and Spoiler surfaces were reduced to subzero temperatures, then subjected to a continuous spray of water until the area was coated approximately 1/2" thick with ice. When commanded to deploy, the system had more than adequate power to break the ice and reach its normal 60-degree position. A similar test with Spoilers deployed during ice accretion demonstrated that when retraction is called for, the panels will return to within 1/4" to 1/2" of flush. This position is well below the airflow boundary layer and creates no significant affect on lift/drag.

All major system components are bench tested before shipping. Hydraulic Spoiler actuators are installed in test jigs that simulate a 300 knot indicated airspeed for one hour. Every PowerPac hydraulic pump is similarly subjected to loads in excess of what it will encounter in normal operations. These tests are designed to show up leaks or other malfunctions.


Quality Machined Components

  • Spoilers Inc. uses computer programmed milling and lathe machines to manufacture all high quality components.
  • Critical parts are machined from solid aluminum alloy billet stock and hardened steel.
  • Finished parts are anodized for lifetime protection and high quality production finish.

Contact Us for More Info about Frequently Asked Questions about PowerPac Spoilers


Cessna 310RCessna 337Cessna 340Cessna 400 SeriesBeech BaronBeech DukePiper AerostarPiper Malibu Mirage

Spoilers Inc.
Spoilers Inc.
1202 26th Ave NW, Gig Harbor, WA 98335
Jeff Shapiro, 253-851-1769

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