Re: Strange buzzing sound on DC-9

Date:         15 Nov 97 16:24:44 
From:         jf mezei <"[non-spam]jfmezei"@videotron.ca>
Organization: VTL
References:   1 2
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Normand Perron wrote:
> Bombardier has one of their major plants in Dorval. When I told a friend
> of hearing a strange noise coming from a landing Challenger, he told me
> that it was probably the ram-air turbine being tested during the
> production test flight. The RAT is a propeller-driven generator which is
> extended into the airstream on the side of the nose in case of a double
> generator failure.
>
> In hudson, any aircraft landing in Dorval would still be quite high
> above ground; a Challenger (or RJ) could be mistaken for a DC-9 when
> there is no possibility to judge the size of the a/c.

That day, there were south-easterly winds which means that planes were
landing "direct" from the west so at Hudson, (about 25 km west of
Dorval), it was a straight line. During more common south-west winds,
airplanes follow the northern shore of Montreal to almost its eastern
end before making a U-turn
to head back to Dorval on the western side of the island. In other
words, the planes were fairly low at Hudson that day because they were
already lined to to land in a direct line. Being about 15 miles from YUL
should give you an idea of
their altitude.

The plane seemed too big to be a CRJ, but I guess it would be possible
although it had fairly large wings whereas the CRJ seems to have much
smaller wings.

Considering that this was a fairly busy lane (saw a few other planes
follow that noisy one), would Canadair have been conducting tests of its
planes in that corridor ?

Interesting though, I had never thought that a RAT would make so much
noise.