Ice, it’s dangerous on the ground and particularly dangerous in the air. The method to remove ice while in flight has remained consistent for decades, while the technology behind these methods has increased performance and durability.
B.F Goodrich invented their pneumatic deicing boots more than 90 years ago as a response to multiple airmail plane crashes caused by airframe icing at the time. In 1932, the company installed the first pneumatic deicing system.
Today, B.F Goodrich’s deicing products are manufactured under Collins Aerospace as Collins Aerospace Goodrich. The company’s pneumatic deicers are used on a wide range of aircraft, including general, business and regional, as well as military platforms – and they work closely with aircraft OEMs to design the deicing system specific to their need and how the aircraft will be used.
“While the system concept is the same, the deicer boot material and/or design will differ between a privately-owned airplane platform and a regional aircraft that will likely have high flight hours. The aircraft OEM may also select the Collins Aerospace silver deicer option for many business aircraft platforms due to customer preference for a metallic look to the aircraft leading edges,” explained Molly Stibaner, senior product support engineer for Collins Aerospace.
Collins Aerospace’s deicers consist of inflatable rubber/fabric boots attached to the leading edge of the wing and stabilizers. When ice begins to form on the leading edge, the boot is inflated and cracks the ice off the leading edge, allowing the airstream to remove the ice. A complete pneumatic deice system consisting of the components such as valves, timers/controllers and switches that support proper operation of the system is offered by Collins Aerospace.
For installation, Stibaner said their deicers are glued to the leading edge. Collins Aerospace’s standard deicers involve the manual application of adhesive to the back of the deicer and leading edge before installation. FASTboot deicers are manufactured with a pre-applied pressure sensitive adhesive (PSA), which eliminates solvent usage, labor and dry times in the installation process.
“The installation of a pneumatic deicer is a unique maintenance procedure that requires proper tooling and technique. Collins Aerospace, Goodrich Deicing provides the necessary information for success through customer training and technical support,” Jeremy Henry, senior program manager with the Collins Aerospace Goodrich De-icing Authorized Service Center Network added.
Henry said that the technology behind the company’s pneumatic deice boots hasn’t changed significantly, but their performance and longevity have been significantly enhanced through the use of newly engineered materials and manufacturing methods.
“While a high percentage of today’s deice boots are still made from the familiar black neoprene, Collins Aerospace Goodrich Deicing is the sole supplier of optional boots made with an engineered polymer called Estane, which provides more resistance to diester fluids with the additional benefit of improved ice shedding,” Henry said.
Estane is also easier to maintain, due to the nature of the improved material.
“In general, the maintenance processes remain consistent even though the materials used may differ. For example, deicers require the application of conductive edge sealer around the edges to allow for proper static dissipation in order to prevent pinhole damage. The type of conductive edge sealer that is used depends on the material of the deicer,” explained Henry.
Knowing when a system needs maintenance or replacing is easy as a visual inspection. Pneumatic deicers should be visually inspected frequently and damage repaired immediately. Unrepaired surface damage can lead to ingress of water into the deicing system, ultimately creating further costly damage to internal components such as valves and sensors, Stibaner said.
Additionally, unrepaired damage limits proper function of the deicer itself decreasing effective ice shed. Collins Aerospace, Goodrich Deicing offers repair kits that are specially developed to repair damage while still allowing for the proper inflation and ice shed of the deicer. The company also offers several products to increase the longevity of the deicers, protecting against weathering and ozone, for example.
However, certain damage requires replacing the deicer.
“These include cuts, tears or ruptures that extend through the bondside fabric layer, broken stitch or thread and damaged areas which exceed 4 inches by 9 inches,” she said.
Stibaner added that the allowable number of repairs is:
- Three small patches per 12” (305mm) square – or –
- Two medium patches per 12” (305mm) square – or –
- One large patch per 12” (305mm) square – or –
- Two small and one medium patch per 12” (305mm) square
- 20 pinhole (1/16” / 4.2mm or smaller) repairs per 12” (305mm) square
Anti-Icing with CAV Systems
Where pneumatic boots inflate to break ice off an aircraft, CAV Systems tackles inflight deicing through liquid means; in fact, CAV Systems' products don’t deice – they anti-ice.
CAV Systems offers two anti-icing solutions, TKS Ice Protection and SLD Guard – the latter of which is designed to protect against the threat of supercooled large drops. Both systems work by releasing a mono-ethylene glycol solution, preventing the formation of ice on the aircraft.
The mono-ethylene glycol solution is released from laser-drilled titanium panels on the leading edges of the aircraft, where the solution mixes with the in-air moisture to reduce the freezing point to -76° Fahrenheit. The moisture is then whisked away from the aircraft by the natural aerodynamics of flight, preventing ice from ever having the chance to form.
Jerry Jordan, VP of aftermarkets, CAV Systems, said they are “strongly into the general aviation market” and also provide anti-icing solutions for military UAVs such as the MQ-1 Predator. TKS Ice Protection is certified for installation on 80 different aircraft models and CAV Systems works with both the OEM and offers retrofits kits.
“In the past 15 years CAV has certified or been closely involved in 10 FIKI certification programs. CAV provides OEM ice protection systems for Textron, Cirrus Aircraft, Diamond Aircraft, Quest Aircraft, Tecnam, Mooney Aircraft, in addition to several UAV manufacturers,” Jordan said. “Additionally, CAV produces and sells aftermarket ice protection systems that can be installed on a wide range of make and model airframes. These include Beech Bonanza, Beech Baron, Cessna 182/206/210/208/350/400, Mooney M20J/M20K/M20R/M20M/M20TN/M20U/M20V, and Piper PA-32 to name a few.”
The titanium panels can be installed on wings, wing struts, vertical and horizontal stabilizers and fixed landing gear. Windshields can be protected via a spray bar and a traditional slinger ring gives propellers anti-ice protection, Jordan said.
“The freezing depressant fluid travels from a tank to metering pumps, filter, through the arterial lines to proportioning units and then onward to the tail and wing leading edge panels,” said Jordan, describing how the anti-ice system works and looks when installed. “So basically, it’s tank, pumps, arterial system, and panels.
“All CAV ice protection system leading edges for the wings and tail surfaces are designed specifically for the airframe of intended use and would not be interchangeable with any other make or model,” Jordan continued. “The fluid motive components, while very similar from airframe to airframe, are typically also unique to the make and model. Many of the system plumbing items are used on many of the CAV installations. CAV has the expertise to provide ice protection on most any type of aircraft.”
Pilots activate the system from the cockpit when flying into icing conditions.
For maintenance, the systems do not require much work. Being made of titanium, the panels only require replacement should they become damaged in the event of a bird strike or hail damage, for example.
“The panels last forever, unless they are damaged from an outside force,” said Jordan. “They’re laser drilled titanium, there really is no maintenance involved with them.”
With respect to the mechanical equipment, Jordan said the filters need to be changed per the OEM requirements, or sooner if a high-pressure annunciation is experienced. Filters should be changed every five years or sooner if a high-pressure annunciation is experienced for the aftermarket installations. Pumps require overhaul per the OEM requirements. Pumps that have been in service for more than seven years should be flow rated tested during annual for those aftermarket installations, to determine if an overhaul is required.
“Garmin has been excellent at integrating with the CAV Ice Protection System. They have integrated very well with all our annunciation sensors. For example, the high-pressure annunciation sensor between the pumps and the filters annunciates the onset of high pressure as the filter reaches the end of its life. This doesn't mean your filters are blocked, it means that they're starting to become blocked and that you need maintenance,” described Jordan.
As such, maintenance is on demand or per the OEM requirements, but Jordan said pilots should be vigilant and routinely inspecting their systems. To make sure their system is ready for winter flying, CAV recommends a pilot do the following:
- Operate the system at least once a month
- Clean the TKS panels
- Replace the deicing fluid filter
- Make sure fluid quantity is at the recommended minimum
