Blades

Blades

When initially purchased, both Canadian H-46 variants were fitted with the same blades. As is evident in the technical drawings below, both variants had blade tips that were not square. This style blade is accurately depicted in the Airfix/MPC model kits only.

Eventually, the blades were changed to those with tips that were squared off although the blade chord did not change as far as I am aware. This is where the similarities between Labrador blades and Voyageur blades end. Structurally they were the same blade visually they were somewhat different; most notable was the colour of the blade tips. On both variants, the forward tips were yellow while the aft blade tips were red. In both cases the tips were painted for the last six inches only with the measurement being made at the trailing edge of the blade. For the purist, the tips colours for both variants were yellow 5-2 and red 9-2.

Early Labrador blades were initially black on the top and bottom with a narrow strip of bare metal, the deicer boot…something Voyageur blades did not have, along the leading edge of the blade. Voyageur blades were painted green 3-17 on top and like the Labrador the black was 10-201 on the underside.

For aircraft 313, the only airframe painted in the variegated camouflage livery, blade colours followed the same pattern as above for tip colour and the top and bottom of the blade. The only difference being the upper blade surfaces were painted green 3-213, not green 3-17. I am presuming green 3-213 is the same colour as the green in the camouflage.

Second-generation blades were metal, but instead of black they were painted aluminum on top and black on the underside. The difference between the first and second-generation blades lies in the ability of the second-generation blade to give aircrew the ability to detect blade problems. The most likely problem being cracks in the skin of the vacuum blades. Sometime after taking delivery the Canadian military, installed on each blade,  a sensor with a moveable component to indicate a difference in pressure of the sealed blade. The newly fitted “Integral Spar Inspection System” (ISIS) alerted the crew to a cracked blade during any of the numerous scheduled inspections. When the pressure inside the blade dropped the moveable component presented what was called a “black” blade leading to a blade change. I have heard stories from older aircrew that the very first blades had to be checked almost constantly resulting in unscheduled landings signaled by a vibration or handling anomaly. In any, case the new detection system called “ISIS” was identifiable on the blades by the “ISIS indicators” located on the underside and near the root the blade. ISIS was fitted on the blades of both Canadian variants.

The only real good picture of the ISIS indicator I could find.

Jeff Wilson's picture show's the underside of an aft blade and a clear view of the red blade's ISIS indicator and a slightly obscured profile look at the green blade's ISIS indicator.

As the helicopters went through the various upgrades, new blades were for a second time installed. The old hollow metal blades being replaced by composite fiber blades that while the same length were wider and heavier by several pounds.  Additionally, where the earlier blades had but one trim tab, it is my understanding, the composite blades had two or perhaps three adjustable trim tabs, although for now I cannot verify this. The composite blades were solid so no longer required ISIS indicators. 

306 sitting on the ramp after flailing itself with the new composite blades. When 304 did the same thing (twice actually) the first time with metal blades, pieces of blade and helicopter were literally sent flying throughout the base (Comox). DND Photo

As I searched for 113 model reviews on the Internet, it dawned on me that comment was required on the need to ensure the counter rotating blades are located correctly. From the pilot’s position, looking forward, the forward blades rotate to the left (counter clockwise) and the aft rotors to the right (clockwise).!