Key to Commander Performance and Efficiency

The key to achieving the best possible cruise performance in a Twin Commander while providing the most comfortable ride and environment for pilot and passengers is maintaining a properly pressurized cabin. It’s not an easy job in any flight-levels-flying aircraft, what with countless locations where pressurized cabin air potentially could leak into lower-pressure ambient air. The people at Twin Commander Aircraft, along with highly experienced technicians at authorized service centers, regularly discuss methods and materials to keep pressurization systems performing at their optimum level.

Over the years, various upgrades and fixes have made significant improvements in the fleet’s ability to maintain cabin pressure. Fixes may be as simple as a seal and as complex as a complete system overhaul. Following is a review of available solutions:

Service Letter (SL) 384, applicable to Twin Commander models 685, 690/A/B/C/D and 695/A/B, describes replacement engine control cable seal nuts to prevent loss of pressurization through the cockpit ends of the engine control cables. Parts for SL 384 are available immediately.

Custom Kit (CK) 50, applicable to Twin Commander models 680, 680F and variants, 680T/V/W, 681, 685, 690/A/B/C, and 695, provides improved cockpit control column and rudder pedal boots. The replacement boots, which are manufactured using more durable material than original factory-installed rubber boots, and the associated mounting hardware last longer and do a better job preventing pressurized cabin air leaks. CK 50 is available immediately.

SL 382, applicable to Twin Commander models 680FP/FLP, 680T/V/W, 681, 685, 690/A/B/C, and 695, surveys areas where cabin air leaks could potentially occur in aircraft pressurized to the floor, and offers a variety of solutions for sealing potential leak areas.

SL 383, applicable to Twin Commander models 695A/B, concerns areas of potential cabin leaks, and solutions, for aircraft pressurized to the skin.

CK 184 and 185 (also known as Harbaugh Seals), applicable to the same Twin Commander models as SL 382 and 383 (above) are replacements for the original molded rudder pedal plugs, which can deteriorate over time. Each kit contains two-piece aluminum fittings that snap around the rudder pedal horns to provide an excellent sealing surface for the improved rudder pedal boots in CK 50. Both CK 184 and CK 185 are available immediately.

SL 388, applicable to all pressurized Twin Commander models, reviews methods for effectively sealing skin laps on the exterior of the aircraft.

CK 183, applicable to Twin Commander models 690C/D and 695/A/B, provides a complete package to replace an existing Sunstrand Environmental Control System with an Enviro system.

Twin Commander Aircraft has replacement ducts for the Sundstrand Environmental Control System in stock for those who prefer to maintain that system.

Twin Commander Aircraft also has parts to replace the cabin door seal (part number 90-935), Emergency Exit seal (part number 330108-45), and floor-panel gasket seals for the 690/A/B/C and straight 695 (part number 320005-67).

For more information

about available solutions for upgrading your cabin pressurization system,

contact your authorized Twin Commander Service Center.