When a co-owner of G-MFHI was out with an instructor last weekend, on
climbout from a successful touch and go, the engine started 'surging' -
repeatedly running roughly then not. A maday call was made and a successful
landing on an alternate runway was executed.
When the cowl was removed and a transparent piece of pipe put into the fuel
line, approximately 30-50% gas could be seen - it could not be determined if
this was air being drawn in or fuel vapour. When the reserve tank was
selected, the gas was seen to disappear and the fuel pump ran considerably
easier.
My problem is that when I went to Rochester today, I couldn't repeat the
symptoms - the pump ran fine from both tanks with little if any bubbles. The
flow rate from the main tank was considerably less (approx 40l/hr as opposed
to 60l/hr from the reserve) - replacing the element in the main tank filter
eliminated the difference.
The aircraft was operating on Mogas, the filter units are the glass type
with metal end caps with a plastic element. The filter element looks to have
quite a lot of fibrous strands in.
My questions are:
1) Has anyone experienced anything like this in the past - if so, did
you get to the root of the problem?
2) There seems to be a thin layer of brown 'stuff' on the wall of the
fuel tank - any idea what this could be?
3) Are these the best filter elements to use - there seem to be more
routes for air to get in that a sealed unit.
Sorry for such a long message but as you can understand, following the
accident at Kemble, it was something of an unnerving experience for the
pilot (and instructor) involved and we really want to find the cause, not
just a case of we think we've found it.
Peter
|