Gavin Grimmer
For quite some time, I found it strange given that Mike had made it very plain that he wanted to continue on with his Flight Plan - to Singleton - and on to Bankstown, yet now it appears that he is rather keen to get to WLM, and this puzzled me for quite some time.… If he had at that point turned towards Singleton, then why had this person see a plane “going in” further east?
Then I noticed something else in the transcripts that may well explain this, and the reason why they never reached WLM, in fact why they have never been seen since!
07:23:54, Mike requested clearance from 8,000 ft to 10,000 ft - which he was granted.
07:29:07 (just a shade over 5 minutes) Mike said he was struggling to get to 8,500 ft... (a shade less than 100 ft/min! Everyone - including me - thought this was due to icing up... but was it?)
07:34:10 Oh hell, we just got in a downdraught now and we’re down at about 1000 ft/min
07:34:43 (Note: After being asked if he wanted to divert to West Maitland:) Nah, ah, we thought we had a .... just to compound things, we thought we had a cockpit fire, but we seem to have resolved that little problem...
07:35:42 We’re up and down like a yo-yo (meaning at the mercy of the wind currents)
07:37:07 7500 ft
07:37:20 We’re having strife up here!
07:37:53 We’re losing a hell of a lot of... we’re down to six and a half
07:38:47 5000!
All of the above ‘speaks’ to me of another possibility, especially when you take into account that a lot of the sightings of MDX claimed that it was on fire, and others commented as it being very noisy, and another thinking it was a “tractor coming up the hill” (pop, pop, pop, pop).... the engine was down on power and not performing as it should!
I have worked the bulk of my life as a mechanic. Not just as a mechanic as a job, but as an enthusiast. Amongst many other things, as far as we know (never found anything to disprove it) I was the first person in the southern hemisphere to develop and actually fly a diesel-powered aeroplane.... not that I wish to make a big thing of this... it’s just to show that I think way outside the square!
To me, I reason that if there is too much fuel being injected into this motor (it had a primitive design of fuel injection on the motor in MDX... by today’s standards), the motor would be down on power and the only fuel that would burn in the cylinders would be limited to the quantity of oxygen ingested into the motor. The excess fuel that was not burnt would be pushed out into the exhaust system until it got to a point where there was more oxygen to allow it to burn. This would result in exactly what many of these eyewitnesses saw... only it was not the plane on fire, but flames coming out the exhaust pipes.... in effect multiple backfiring noises that would be very noisy and sound like a pop, pop, pop, pop noise.
Have a look at these two videos and it will give you some idea of the flames:
https://www.youtube.com/watch?v=jCkRQ0IlG34
https://www.youtube.com/watch?v=i0doQF11bhU
Take note of this part of a Cessna 210 Centurion article:
The electric auxiliary fuel boost pump is NOT to be used in flight except in an emergency. Unlike some other high-performance airplanes, and even some other Cessnas, it is not supposed to be operated during takeoff, on approach, during maneuvers or while switching tanks (unless you have actually run a tank dry and the engine has begun to lose power or has lost power completely). If you run the electric auxiliary fuel boost pump while the regular engine driven fuel pump is working normally, this will cause the engine to receive about twice as much fuel as it needs and cause it to lose power or even stop running.
The electric auxiliary fuel boost pump consists of a split rocker switch located on the lower left side of the instrument panel next to the master switch. The left side is red and the right side is yellow. The left / red side is HIGH; the right / yellow side is LOW. The HIGH side will be required to keep the engine running at high power settings such as takeoff and initial climb. The LOW side should be adequate to keep the engine running at cruise power settings, depending upon conditions. (Ed: I presume this last paragraph is in the event of a failed mechanical pump, as the previous paragraph says not to use it)
For safety, in most of the earlier 210s the HIGH side is spring-loaded to the OFF
position. (That feature was eliminated in some later models.) This means that if
you bump against it, it will automatically turn itself off when pressure against
it is released. The LOW, side, however, will tend to remain on. This is so that
you do not have to continuously hold pressure against the switch while flying following
a fuel pump failure.
The electric auxiliary fuel boost pump is normally used to prime the engine before starting, however, and the procedure for this is listed in the Flight Express Initial and Recurrent Flight Training Handbook.
MDX pg 38