"There has been much speculation, but no contact with myself or Hunter Flying Ltd which maintains Miss Demeanour, to find out the facts about the fuel venting at the weekend. These are the facts:
"Miss Demeanour vented some fuel and air at high power settings. This was brought about by one (of several fitted to the fuel system) pressure relief valves operating to relieve air pressure used to pressurise the fuel transfer system. Indications in the cockpit showed that the air pressure, known as the Transfer Pressure, was actually normal.
"The amount of fuel vented, or the rate of venting, can be compared to mist or steam in that it appeared outwardly copious, but in reality, was imperceptible on the fuel gauges. Investigations as to why the venting was taking place were carried out and valves checked and changed. These changes required the flight of the aircraft to confirm success, or failure, of the rectification."
"The display on the Sunday was cut short because it was obvious that replacing the last valve we checked had not fixed the problem. It would have been possible for Miss Demeanour to participate in the mass formation as on Saturday, as that flight had shown that such a display could be carried out without venting, but a decision was taken not to.
"By a process of elimination, we had isolated the sequence of valve positions that were causing the problem. We had also established that the venting only took place at high power settings (above 7200rpm) and that she did not vent fuel at normal cruise power settings of 6600 - 6900rpm.
"The cause of the venting was the sticking of the Refuelling Pressure Relief Valve. This comes in to operation during refuelling to protect the aircraft's tanks from being over pressurised by the fuel bowser and operates at a lower pressure than the series of normal Fuel Pressure Relief valves."
"With this valve stuck in the Refuelling position (there is no external indication), when the air pressure from the engine rose to maximum at high power settings, it allowed the air to vent along with fuel. There are two vents, port and starboard, inboard and in front of the wheel wells and these allow *safe* venting. That is their purpose.
"At no time did the venting jeopardise the aircraft's safety or integrity, nor anyone else's, apart from the smell of JETA1. The final take off from the Cotswold Airport was followed by a flypast of the tower at cruise speed and power. This was to demonstrate that the flight back to Exeter could be made without venting."
2011-06-24 - Tony Exelby
Jonathon,
Thank you for the explanation, i cannot understand why people who are not in the hot seat like youself give out stupid comments.
I saw the venting but never gave it a second thought.
Why so much pathetic comment from people who probably do not understand aircraft engineering.
Many thanks for such great fun watching you over the years, i remember when G-PSST was rolled out at Bournemouth for the first time and just loved the scheme.
Hope the Maserati is still running.
Best Wishes,
Tony
2011-06-23 - Robin
Mr Whaley,
Thank you for a detailed and professional response to a lot of uninformed comments. Thank you, also, for the enjoyment you have given me while I have watched and photographed your displays over the years.
2011-06-21 - Pete
Glad to hear that Jonathon and Miss Demeanour were in no danger and the problem has been rectified. looking forward to seeing Miss D at RIAT this year as I have never see Jonathan display except in video footage.
2011-06-21 - James P Maher
Having read many comments on various forums, it is nice to see the facts rather than idle speculation. Which is in most part knee jerk reaction.
As an ex-serviceman myself whose expertise lies in refuelling, I have come across this problem on more than one occasion.
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