Sunday, 1 January 2012

Aft Pylon - Functional Features

Aft Pylon
Likely, the most noticeable difference, to the educated, between Labradors and Voyageurs is the inclusion of a tail mounted auxiliary power unit (APU) on the Voyageurs.  In addition to a change in the basic profile of the tail, the auxiliary power unit installation meant relocating, albeit only a matter of inches, the white aft navigation light.

Labradors began life without auxiliary power units relying on start carts to power up when starting at home bases or suitably equipped airports.  The nature of search and rescue work, however meant operating unsupported in remote areas where start carts were a luxury they would have to operate without.  Labradors therefore relied on very taxing and potentially dangerous battery starts.  The solution was to strap a portable APU cart on the ramp.  It was not until late in SARCUP that Labradors were modified with a tail mounted APU. 305 For one was not modified with a Voyageur tail until after 1980, and was probably one of the last, if not the last, airframe to be modified with the new tail and APU.

Because of unspecified incidents, Labradors 404 lost it’s rear end shortly after being purchased and was fitted with Voyageur style tail early. Aircraft 402 however lost its tail in a landing accident at Coldfish Lake, B.C. in November of 1968. In both cases, while Voyageur shaped, the new tail did not include the APU.  The opening for the APU exhaust being blanked off and the navigation light relocated accordingly.

Another aft pylon feature that differentiated the two variants was the addition of drain covers on the Labrador.  Most pictures of Labradors wearing the 400 series numbers reveal that early Labradors did not have drain covers, while those in300 series numbers always seem to have the covers. The covers were fitted over all drains on both sides of the aft fuselage.  This difference also remained until the aircraft were retired.!

307 Without drain covers - Photo Derek Heyes

Note three things from this photo - 1) 301 does have the APU installed in the tail, 2) drain covers remained on both sides of all Labradors to the end, and 3) blade inspection lights were installed as part of  SARCUP, I believe.

415 in Army livery was delivered with a tail mounted APU.

Another photo of a SARCUP Labrador with tail mounted APU - Photo Jeff Wilson
A A final note on the aft pylon is about the blade inspection lights mounted on both sides of the aft pylon. It appears that Labradors were fitted with the lights first, while in red, white and blue livery, but after the helicopters were using the 300 series numbering, whereas Voyageurs were not fitted with the lights until SARCUP.

In the above three photos, note that the blade inspection lights appear to have been installed when 305 had entered the era of "CANADA" titles. This may not be the same for every aircraft though.

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