Speedbrake Mods: Questionable For Some

Precise Flight SpeedBrakes and PowerPac Spoilers can more than double descent rates without power chops or Vne busts. Consider your mission, engine and skills.

Some OEMs include speedbrakes as standard or as an option on new aircraft, and they’ve been available for years as STC’d retrofit systems. Fitting speedbrakes in the aftermarket may seem like a complicated project, and while it’s a major modification, the installation is easier than you might think—as easy as cutting holes (rectangles, actually) in metal wings can be, that is.

In this article we’ll look at the two and only aftermarket speedbrake systems, the installation, real-world use and the cost.

Spoilers or Speedbrakes?

Technically, speedbrakes are spoilers because they spoil the airflow over the wing. Confusing the matter is Precise Flight‘s product— the electric SpeedBrake 2000 system.

There is also the PowerPac Spoilers system from Spoilers Inc. It offers a number of STC’d kits for twin-engine aircraft retrofits, including twin-Cessna models, the Beech Baron and Duke, the Piper Aerostar, plus the Piper Malibu/Mirage singles.

Whether you call either spoilers or speedbrakes, the marketing push for each comes down to, well, coming down—fast—without an engine-shocking power reduction.

Considered a third dimension of flight control, wing lift spoilers make for easier speed reductions to gear extension speed, combat ATC slam-dunk descents, plus extend high-altitude efficiency closer to the runway.

PowerPac’s STC allows for spoiler deployment and retraction in icing conditions, while Precise Flight’s SpeedBrakes aren’t approved for use in visible ice.

Both products have been around for years, resulting in engineering improvements that contribute to better failsafe capability while also taming installation complexity.

Hydraulic vs Electric

PowerPac represents its spoilers as the “jet-type” design, similar to the plate-like spoilers on big airplanes. PowerPac says these are designed to reduce lift, rather than merely increasing drag.

PowerPac spoilers are hydraulic, and all retrofit kits (except the one for the Aerostar) employ an electric-hydraulic pump (called the PowerPac) to supply hydraulic pressure for deployment/retraction. The kit for the Aerostar consists of a manifold that directs hydraulic pressure from the airplane’s own system to the spoiler system actuators.

When deployed, they extend upward into the slipstream at a 60-degree angle, spoiling a portion of the lift being generated by the wing, while at the same time creating drag. When retracted, they stow flat in the top surface of the wing.

For an added layer of failsafe, the system uses limit switches on each drive servo motor to close off the flow of hydraulic pressure. This triggers a logic signal to the panel-mounted status annunciators for each spoiler. The spoilers are deployed and retracted with a single push-button switch, which applies power to the hydraulic pump.

During electrical failure, the solenoid valve opens, sending hydraulic fluid back to the reservoir, while the aerodynamic pressure and return springs on each plate immediately retract the spoilers into the wings. You can initiate a manual hydraulic dump by pushing the switch twice.

Spoilers Inc. says its target performance for the product is an increase in descent rate of between 50 and 100 percent of what it would be without them. The spoiler plates are designed to minimizing rumbling and drastic changes in pitch.

As part of the STC process, the spoilers were stall tested with all possible combinations of gear position, flap position and CG range, proving no adverse change in stall characteristics and no substantial increase in stall speeds when deployed.

The spoilers are made of aluminum alloy, weigh 20 pounds when installed and are fully deployed within four seconds.

As for installation, Spoilers Inc. suggests upward of 45 hours of shop labor for the aircraft on its STC. Add at least seven hours to that if your shop has never installed them. Installation time can increase by 20 hours if the aircraft is STOL-equipped. List pricing of the hardware ranges from $7000 to $9500, depending on the kit.

Precise Flight

The SpeedBrake system was Precise Flight’s first product. Originally offered in 1980, its current SpeedBrake 2000 system is standard equipment on new Mooney, Beech, Piper and Cessna Corvalis models, while a similar kit is offered to the aftermarket through STC retrofit. The SpeedBrake 2000 is also provided from aftermarket modifier Knots2U.

The aluminum system is electrically driven and operates quite differently than the PowerPac Spoilers. It uses no hydraulics, cables or pulleys and the blades stow flush with the surface of the wing when retracted. Precise Flight says its SpeedBrakes can double the descent rate, while reducing airspeed by an average of 20 knots. SpeedBrakes are deployable up to the aircraft Vne and have no overall speed restrictions.

The scissor-like aluminum blade cartridges are attached inside each wing using stiffeners, doubler plates (which strengthen the cutout areas) and retaining brackets. Precise Flight provides bare-ended wiring harnesses, which terminate in a central bay location and connect to the ALC (asymmetric logic control box). The logic inside the ALC ensures that both brakes deploy at the same time, while a panel-mounted on/off actuator switch and status annunciator panel is used for primary control.

Operation is straightforward. According to the flight manual supplement for the Beechcraft Bonanza series, expedited descents are accomplished by setting 2400 RPM and approximately 16 to 18 inches MP, followed by SpeedBrake deployment. In the landing pattern, the FMS states to fly a high base and final leg, extend the wing flaps and then deploy the SpeedBrakes. You can use the SpeedBrakes intermittently to modulate the glidepath.

Precise Flight says that experienced installers can retrofit the SpeedBrake system in roughly 25 hours, but the average installation time is more like 35 hours.

The typical price of the kit is around $5000. For fiberglass aircraft (only the Columbia 300 is approved for retrofit), a prefabricated fiberglass pocket is grafted into each wing for housing the SpeedBrake cartridge.

Precise Flight says you might be able to earn FAA field approval for aircraft not covered by the STC, but you should expect the process to be extensive and costly.

Worth the Investment?

As Rick Durden describes in the sidebar on page 10, there are some compelling operational benefits to speedbrake retrofits—perhaps more compelling for finicky high-output engines.

RAM Aircraft is one engine builder that advocates the use of PowerPac Spoilers to help combat engine shock cooling, particularly for RAM-modded Cessna twins. Given the nature of the installation, we think selecting an experienced shop—or at least one with expertise in sheet metal work—is imperative. RAM is one of them.

But for lesser aircraft (we’re talking about Archers and Skylanes, to name a couple), we don’t think attempting a field approval for installation is worth the chase. But if you fly a high-performance piston in regions where slam-dunk approaches are the norm rather than the exception, or are concerned with chilling the engine while throttled back in a last-minute descent, we think either product is worth considering.

You might also consider passenger comfort and airframe stress. Speedbrakes and spoilers can avoid the drama of uncomfortable nose-down descents, while allowing for a slower ride while descending through turbulence.

Last, we disagree with those who say speedbrakes are a substitute for STOL mods. Good speed control on final is what efficient and shorter landings are made of, and speedbrakes and spoilers can help get you set up for it before hitting the traffic pattern.

Larry Anglisano
Editor in Chief Larry Anglisano has been a staple at Aviation Consumer since 1995. An active land, sea and glider pilot, Larry has over 30 years’ experience as an avionics repairman and flight test pilot. He’s the editorial director overseeing sister publications Aviation Safety magazine, IFR magazine and is a regular contributor to KITPLANES magazine with his Avionics Bootcamp column.