Saw a magazine photo of the HARS bound Convair 440 departing its overseas base for Australia. Nice photo in its TAA colours. What intrigued me however, was on the one engine you could see from the camera angle, one of the two cowl flaps situated on the top of that engine, was fully open. The lower two flaps at the underneath of the engine could not be seen. It may be that particular Convair had the lower cowl flaps removed.
RAAF Convairs I flew had bottom and top sets of cowl flaps. These were essential for ground running as the closely cowled engines needed airflow to prevent overheating of the cylinders. That is why the cowl flaps were selected to fully open on the ground. In the case of the HARS departure with one of its top cowl flaps fully open I wondered if the cowl flap motor was inoperative right from the start? Perhaps lack of spares and the costs involved with delays, the crew decided to depart and get going for Australia asap and wired that top cowl flap fully open to keep the engine temperatures down during the take off and climb - especially if the weather was going to be hot.
The problem with that, would have been the performance penalty would have been significant due to the extra drag of the open cowl flap - especially if an in-flight engine failure occurred on either engine.
In the Sixties, the RAAF had a similar event like that while on the ground at Charleville en route to Darwin. The cowl flap electrics failed for the top cowl flaps on one engine. After discussion with the airman engineer who flew with the Convair, the pilot had the engineer manually set the top cowl flaps on that engine to the take off position called "trail" which was almost the closed position. Taxy to the runway was then done on one engine (good nosewheel steering).
On line up, the engine with its cowl flap already wired at the trail position, was started and when temps and pressures were within take off limits, the aircraft departed normally. On arrival at Darwin after an uneventful flight, the pilot shut down the engine (with the cowl flaps fixed at the Trail position) at the end of the landing run and taxied in on one engine. This was because the after landing drills required all cowl flaps to be set to fully open to have cooling airflow over the cylinders during taxying.
The problem was a failed top cowl flap motor which was soon rectified at Darwin. The drag from a fully open cowl flap in flight would have been significant if indeed that was the case of the HARS Convair.
There are always two sides to a story and it would be interesting to know what caused the HARS Convair to depart from its overseas base with a fully open cowl flap?