AIRFRAME
BRRR…IT’S COLD OUTSIDE Tanis Preheat Systems for Helicopters
R. Fred Polak | Editor in Chief
Preheating an aircraft is not what I would normally be thinking about while I am in my office in Glendale,
AZ, about four miles north of the Phoenix Cardinals Football Stadium. For the past few weeks, temperatures have been averaging around 112 degrees. Although in retrospect, if you operated a helicopter or fleet of helicopters where winters got pretty cold and you were thinking about installing a preheat system, now is the time you would get it done in preparation for old man winter.
Why Tanis Preheat? According to Dirk Ellis, Tanis engineering manager, “Tanis manufactures the only Heli-Preheat system that thoroughly and safely heats all critical helicopter components including engine, engine reduction and accessory cases, oil, hydraulic tanks, fuel control units, and main and tail rotor gear boxes. Direct application of heat assures thorough heat is applied in a safe reliable manner which reduces maintenance costs and fuel consumption. Quite simply, preheating adds to operational reliability, utility and flight safety, ensuring reliable starts in all weather conditions.” Doug Evink, Tanis president and CEO, states, “Tanis stands for the most technologically-advanced aircraft preheat systems. A Tanis system is the only solution to provide heat to all critical helicopter components.” The preheat system is not used in flight. Systems are
available in two separate voltages: 115vAC and 230vAC. Power is provided by a ground/shoreline source. The system is not connected to or dependent upon any existing aircraft systems. Voltage requirements are identified by power plug type, placards and flight manual supplements. Circuit protection requirements do not exceed 12 amps. The 115vAC and 230vAC systems not only differ by power
requirements, but component part numbers also identify voltage requirements. These parts include the power plug,
indicator light and heating elements. Voltage dependent parts use the same installation process, locations and wiring kit. Preheating the aircraft components is accomplished through heat pad elements mounted to the components surface with an approved bonding adhesive. Power is applied to the heat pads through an independent wiring assembly that is routed with existing wiring using accepted shop practices. The photos that are shown in this article are of some of the places where the Tanis preheat pads (flat and orange colored) are installed on a Bell 429 helicopter. The photos are provided courtesy of Tanis Aircraft Products.
How Long to Preheat? Tanis representatives state that its preheat system is designed to “heat soak” an aircraft engine to approximately 60 degrees over ambient temperature in approximately six hours. This is a general guideline dependent on variations in systems and engine applications.
MX Issues
Unable to Start Due to Cold Weather The main reason that a turbine engine will not start when cold soaked is that the gear boxes and bearing surfaces are going to be tight due to thermal expansion of the different metals and other materials. This means that the bearings (which might be steel) are housed in an aluminum box running on stainless-steel races and are all going to be at the extremes of their normal operational tolerance. When at extremes they might not function together properly. This is compounded by the fact that when you try to
start the engine, you are basically throwing fire at the vanes, heating them until everything comes back into tolerance and the shafts and bearings can move freely.
Engine AGB Lower RT 6
HelicopterMaintenanceMagazine.com December 2014 | January 2015
Engine Oil Cooler
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