Well they did undergo the SLEP..

It’s Avon engine is regarded as one of the most robust engines ever built by Rolls Royce. It is still used by power stations for auxiliary power generation. The London Underground also used them, I think again as an auxiliary power source or something to do with ventilation. Why? because they ran for hour upon hour with faultless reliability. While I was flying in the Fleet Air Arm, we had a Rolls Royce engineer talk to us about the Phantom’s engine. He had also worked on Avons. We still flew Hunters and I asked him how long could the engine run without oil pressure. I think his reply was something on the lines “we gave up try to find out after eight hours”.

Interesting points DP.
The Avon series are long serving but the term robust should be qualified. The Avon engine was evolved from an unsuccessful attempt called AJ65. When they carried out the compressor tests it was found that at most rpm levels it was running in deep stall margin, which would cause the engine to stall/surge. To compensate for this the compressor was re-designed, the first few stages were limited in raising pressure/temperature in the same way as the Sapphire engines. Also, airflow was controlled by the use of variable inlet guide vanes (VIGV’s) and a compressor bleed valve dumping air from the latter stages to increase the axial air velocity, improving the stall/surge margin. Due to the materials used, the running time before overhauls was 500-600 hrs, which compared to more modern engines is quite low. The proportional fuel control unit is a complicated hydro-mechanical system using variable delivery pumps and a host of regulaters that trim the flow according to rpm, altitude, temperature and acceleration demands.
Being complicated, that can also go wrong at an inconvenient moment XG197 at Tintagel is a good example. I’m not saying that is the reason for this tragedy, but it does highlight the point that something ‘minor’ can cause major problems. A small blob of grease causing the engine to stagnate….
Your point about the Avon being used today still at pumping stations is correct but those versions have much more simplified airflow and fuel control, they don’t need to compensate for sudden altitude changes. Plus they run at an optimised rpm with little variation, that makes them more reliable.
I will repeat what I and a number of people have already posted. Instead of speculating, wait until the AAIB release their interim or definative report. They know what they are doing, they are very good at it…

I did point out that it was not just the a/c. Maintenance was also not optimum in the beginning. On the early versions the use of downward firing ejection seats also had limitations. I believe the G’s were eventually fitted with MB mk 7 zero-zero seats.

If I remember correctly, Germany lost about 200 a/c with about 110 fatalities. That does sound high in anybodies book. The factors surrounding the mishaps were diverse.

Agree.

Yes and a rather outdated one.
Try and compair thrust output.

Thrust = mass airflow x delta V.
Also, try climbing into one yourself. They are tight.

One other point. The later generation Lightnings (3,5 & 6) had such an increased mass airflow engine the intake could not supply enough air, that full reheat was modulated until the a/c reached about Mn 1.4.
That’s what happens when you add a zero stage…

am I right in thinking that an attempted low-altitude ejection in this case would have been a futile exercise?

I believe it is a mk 4 zero/90 seat (90 knots forward speed is good for zero altitude ejection) fitted to the Hunter.