Comments on the Avon "200" upgrade package.

[f4dj79]

Howdee
I wanted to toss in a responce to thermal coatings. Robin and S&S Turbines re-built our J-79 and updated the hot section with thermal coatings. We know first hand that these coatings work very well. The North American Eagle run our engine with kerosene and white gas to raise the BTU output and we can run the RPM's up to higher setting. This gives us more power through out the military throttle settings. Without these coatings the J79 would not handle the extra BTU output. We had an incident were excess fuel got into the liner area and lit off. We re-fired the engine and blew out the problem. After doing a check of the hot section it was determined that the coatings did their job and protected the metal. I do not recommend this procedure be done to often, but is go to know that with coatings there is a fudge factor and accident protection. We know all to well what happens to an un-protected engine, we over tempt and cooked an engine and even spit parts out, (not something I am proud of) the metal was exposed to 1200deg or more temp and the blades did not handle those temps. With the coatings Robine figures we could handle 1200deg maybe more. We run our engine in the dirt on the lake beds and the other thing coatings can do is protect the metal from erosion in this case the coating will ebrade away from the silt and sand ingestion. This does not cure the compressor blade erosion however ever little bit helps. I am a believer in thermal coatings!
The RB211 and GE90-90-100-115 use the theraml coatings to control heat related issues in turbine section. We have expirenced a few hot starts and shut down mistakes. Without thermal coatings we would be changing engines. Granted when over temps happen we do borescopes to verify possible damage. The old J79 does not have borescope capability's so we have to rely on visual inspections as best we can. The engine will be removed this winter and freshened at S&S Turbines. During this time we will look at how the enigne is holding up to the abuse.
WB

[j79guy]

[Taylor, David H] Wrong. The writer has completely misunderstood the design of the swirler burner.
[Taylor, David H] Wrong. The swirler burner has been the standard for several years and was first introduced in the mid 1990's. Many operators have changed to the swirler burner and have benefited from the ensuing benefits.

Misunderstood? Please explain in detail how then the “Swirler Burner” actually works. The Avon DLE system was not a successful retrofit from the Industrial RB211, and the “Swirler Burner” is a modest modification to the fuel injection nozzle design. The standard? I think not. Of the 1,200 odd Industrial Avon units produced over the years, the vast majority of the natural gas fueled units have a regular diffusion nozzle, interchangeable across all the models. “Upgrade” to the “Swirler Burner”, and you lose this commonality, and pay more to boot for the nozzles. Please show me I am wrong. Do not just say I’m mistaken.


[Taylor, David H] Wrong again. The writer clearly has not researched the costs of upgrading to Avon 200.
[Taylor, David H] Wow. 60% x $3 million USD is an expensive overhaul for an Avon engine. Rolls-Royce authorised overhaul bases can provide a much more competitive price and have OEM backing.
Taylor, David H] Ask Rolls-Royce for an Avon 200 quote for comparison. Then choose.

It was one of your direct customers who invited me to inspect your pricing, for the last A200 “upgrades” done to their Avon units. Research was not necessary; your all-up pricing for each unit was there in black and white. I stated that economical alternatives exist for Avon operators at LESS THAN 60% of the costs for the A200 “upgrade”, which results in similar or better reliability and thermal efficiency.
At least we do agree on your last statement. I fully encourage all operators of Industrial Avon units to fully investigate overhaul and “upgrade” costs. I also encourage them to look at other costs such as; Total Per Fired Hour Maintenance Costs. Warranty claim frequency rates. Customer Satisfaction, and Field support.

Robin Sipe.