The Gnat Handling Flight — Overview

By Air Mshl M S D Wollen (Retd)
  The Gnat was selected for the IAF in 1954, whilst in development at Folland, UK. It was a bold decision. A senior test pilot (Suranjan Das) was seconded to Folland to assist in development of the aircraft. Aside from India, the only other country interested in the Gnat was Sweden (they purchased 12 aircraft). A small team of senior IAF officers was also deputed to Folland to oversee development. The first Gnat came to India in Jan 1959 ; it flew in the Republic Day Flypast.
2. The Handling Flight formed in Dec 1959 with 6 Gnat aircraft, 4 pilots, 1 engineer officer, around 50 airmen and 10 lascars. It formed the “B” Flight of A&ATU, Kanpur, under the command of Wg. Cdr. Suranjan Das ; its tenure was one year. Its main tasks were:–
  (a) to recomend spares, required for future Gnat squadrons.
  (b) to verify the Gnat’s capability to perform ground-attack missions (guns,rockets, bombs).
  (c) to verify performance of its fuel-dip system, which enables complete fire-out of its guns at 45,000 ft.

3. These were simple tasks for a developed aircraft. Unfortunately a number of aircraft-systems proved to be faulty. Four such systems are mentioned below :– 
  (a) The most serious and complicated fault lay with its slab-tail control,the Hobson Flight Control Unit (a larger version performed well on the twin-engine Lighting aircraft).
   Two test pilots had been killed ; one at Kanpur in early 1959, the other at HAL, Bangalore in 1960.

Wreckage examination revealed the slab-tail was in the ‘full nose-down position’, whilst the pilot’s control column was in the ‘full nose-up position’. This could only happen if there had been a ‘trim runaway’.

Numerous mods were introduced, with switches in the cockpit to isolate the FCU. The cause of failure was never established. The last accident of a similar nature occurred at Pathankote in Nov 1971.

The Bouche Committee recommended several measures, which were physically incorporated by HAL, under their Chief Designer Mr. Vardarajan. This was achieved in the mid-1970’s. No further failures took place.

(b) Malfunction of the Glouster fuel-flow proportioner (due to deterioration of rubber components). Flame out by two aircraft in 1960 was probably due to fuel starvation, caused by fuel-flow proportioner malfunction. When drop tanks were carried and improper fuel-flow occurred, the c of g moved aft, making landing hazardous. Drop tanks had to be    jettisoned, before landing.

   (c) Failure of rubber seals in the hydraulic system. After a case of blockage of the filter in the starboard aileron servodyne, leading to the control column jamming in the fully port position (the pilot had followed the ’emergency drill’ specified in the Company’s Pilots’ Notes ; the aircraft had reached landing-flare-out height at Palam’s RW 33, when the emergency arose). The PN’s were immediately amended and one more mod    introduced, whereby the pilot could select manual aileron control instantly (both aileron servodynes hydraulically blanked off).
(d) The radar ranging system was unreliable ; proved during trials at Jamnagar A/A range in Apr 1961. Manual ranging of the GGS was most successful against banner-towed-targets.
4. In Apr 1960, the Flight ceased air operations for 5 months. All Gnats of A&ATU underwent an improvement mod programme. The tenure of the Flight was extended by 4 months to the end of Apr 1961.
5. Several mechanical problems rose in later years. Two are mentioned. (This author had been closely connected with Gnat operations). (a) Gun stoppage, due to faults in the cross-belt, gun feed system, occurred during the 1965 war. Pak aircraft, escaped being shot down.(b) Breakage of the undercarriage radius rod, during the landing-run, caused violent pitch-up and the aircraft went off the runway.
 6. The Handling Flight generated spares consumption data. It verified the aircraft’s capability to perform all ground attack missions (guns, rockets, bombs) at Tilpat A/G range. Its fuel-dip system was proved to be efficient during gun-firing trials at 45,000 ft at Jamnagar A/A range.
 7. In conclusion, the Gnat was most effective in the wars of 1965 and 1971, but it was ‘accident prone’ throughout its ’30 year-service-life’.

4 thoughts on “The Gnat Handling Flight — Overview”

  1. The hint of the story at para 3(c) above needs to be recoded in juicy details. May I request Air Marshal Wollen to please tell us the story at his informal best style?

    Tiku Sen

  2. Sir,
    Just a minor point on Air Marshal Wollen’s excellent article. It says the only other country to fly the Gnat fighter was Sweden. In fact it was Finland. And Yugoslavia also bought 1 for trials – but Finland was the only other country to fly it ops.

    Finland even had an FR version of the Gnat with cameras in the nose.


  3. Received from an anonymous source.

    RAF’s experience of trouble in an inverted flight: –

    Jack Dean.
    Gnat Inverted Test Flight
    Wed Nov 5, 2008 4:15PM

    A story that turned out OK but might have had a different ending.!!!!!!.

    During the time we were servicing the Gnat aircraft for the RAF when they were completed and what we called Off Test they were collected by RAF pilots or sometimes delivered by our pilots back to their Station.

    This particular aircraft was on delivery flight back to the RAF when the pilot decided to do a few tests.{not sure if it was an RAF pilot or one of ours}.

    During inverted flight the Jet Flamed out and the pilot had to make an emergency landing with no engine. Fortunately he was a skilled pilot and managed to get it down safely.

    Think it was at RAF Wittering.

    Of course there was a big enquiry and it was found out that an inverted fuel valve had been fitted incorrectly. So instead of
    supplying fuel to the engine on aircraft inversion it cut the fuel off.

    There was a lot of heart searching and discipline back at Bitteswell.

    Don’t think anyone got fired but believe there were some suspensions in the Mechanical & Inspection Departments.

    Thought this might be of interest. Just shows how snags can be missed even in the most thorough systems.

    Jack Dean

  4. “It was flown by Sudhakaran in the Republic Day Flypast of 1958.”
    Extract from “Development of the Gnat at Folland – Uninspired Guesses ”
    “The first Gnat came to India in Jan 1959 ; it flew in the Republic Day Flypast.” Extract from Gnat Handling flight – An overview .
    I remember reading at other post by W/C I M Chopra that the first fly past of three ac was flown on 26 Jan 59 and Sudhakaran may have flown single ac on 26 Jan 58 .
    As we are celebrating 50 years of Gnat in 2008 , I presume that the Gnat did come to India in 1958 and did first fly past on 26 Jan 1958 .
    Also hats off to Anand deep Pannu for encyclopaedic knowledge on matters of the IAF and the Gnat .

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