By Air Mshl MSD Wollen (Retd)
The Gnat Handling Flight (GHF) moved to Palam in the second week of Jan 1961. It had completed its last phase of air to ground, 30 mm cannon firing at Tilpat range and was due to move to Jamnagar to complete its final task viz.,prove the effectivness of engine fuel-dip system, during cannon firing at 45,000 ft over the Porbunder A/A range.
2. On 11 Mar 61, I took off in the early evening (my third sortie of the day) in Gnat IE1067, to carry out a post 100 hr flight-inspection. The aircraft was fitted with unfilled drop tanks.The Gnat aircraft fuel flow proportioner had in recent months been malfunctioning. During the climb out, the aircraft’s ‘c of g’ was thought to be moving aft, since fore-aft movement of the control column did not result in precise response (a typical sign of flow proportioner malfunction).
3. The emergency drill in such a case was to split the tail-plane, shut off hydraulic power, retain ailerons in power (ie not exhaust power by small aileron movement, thus bringing the ailerons to manual) and land. This drill was followed, since it is stated in the Company’s Pilots’ Notes. On the final approach to R/W 33 (Palam’s main R/W was under renovation), at about “flare” height (undercarriage down, ailerons drooped) the control column moved fully left ; it could however be moved forward/backward. The aircraft rolled to the left ; the airspeed was around 150 kts. I slammed the throttle open and gained whatever height was possible before the aircraft reached the 90 deg. banked position. The rate of roll could not be hastened or slowed. On my back, I gained more height. The aircraft entered a second roll ; I re-selected hydraulic power ‘on’. Movement of the control column was restored. I landed the aircraft with the tail plane split. No over-sensitveness in controlling pitch, during landing, with an aft ‘c of g’, occurred.
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