Most recent aircraft with water injection?
 

I hope this question is technical enough for this forum; if not, I apologise.

Some early 1970s Boeing 747s with Pratt & Whitney JT9D engines allegedly had water injection. Was there anything since then, or has the concept been abandoned?

Improved materials, metals, and cooling have basically eliminated the need for water injection. While water injection would still 'work' (cooling the air coming into the combustor so you can add more fuel without over temping the turbine), it has plenty of downsides. First off, you need to carry the water and associated equipment (added weight and cost), you can't use any water - it has to be reasonably pure (distilled being ideal), there are corrosion issues, you need to keep it from freezing, and (depending on where you inject the water) it can cause blade erosion.
Modern turbine engines use such specialized materials, manufactured methods, and turbine cooling allow very high turbine inlet temperatures with impressive reliability and time between overhauls without the complexity and issues of water injection.

There used to be separate 'max rated thrust' numbers for 'wet' (i.e. with water injection) and 'dry'. Turbofan engine ratings no longer make that distinction because I don't think anyone has certified a new engine with water injection in 50 years.

I believe the E-8 JSTARS and the E-3 AWACS, which were the last of the 707 production line, were delivered with water injection when delivered in the early 1980's so a bit later that the 747. I asked a JSTARS pilot around 2022 (shorty before the airframe was retired) if they ever used water injection and he stated they were still fitted with it but had not used it for many years.

Thank you!

The Harrier.

Some versions of the Metro in use (definitely the II) use water/meth (CAWI), I'm not sure if the 23 had it, but on the II (which I was flying a couple of years ago) we used to use it, mainly peak summer, short strips etc. If it didn't come on symmetrically or failed to fire you definitely knew about it!

Thank you, and Chesty Morgan!

Wikipedia says the 1980 SA227-AC Metro III had alcohol-water injection, too.

Bae J31 : Water Methanol Injection ordered by Skywest Perth Wa
 

Hi
Bae did a demo tour of Australia (including Perth Wa) with the J31’s and the TPE Garrett Engines around 1990 (?) but without any water methanol injection .

The performance figures did not stack up in hot Summer Climate conditions.

Skywest asked for Water Methanol Injection to facilitate “Hot and High” performance and Bae obliged with Skywest Airlines being the first to operate that configuration in the J31 .

Of note TAA in Australia had Water Methanol Injection on the F27’s for the Rolls Royce Dart Engines .

Cheers
Buddy

I found it was more a stop gap measure when existing designs reached a singular limit until a newer design could replace it. For example, Bell released the 206L helicopter in the mid-70s that required water injection with the installed Allison C20B engines. However, by the late 70s Allison came out with the C28 engine which dropped the injection requirement that led to the 206L-1. Regardless, water injection is still used in some special aviation activities like racing.

As dijon moutard mentions, the BAe JS31 had water methanol injection. I don't recall if it was an option or standard. Very much a similar generation as the Metro, possibly slightly more 'recent' depending on the qualifier. Certified in 1982.

The ones I flew had long had it deactivated/removed though.

Flew the “Straight” 206L with water injection a lot …it was interesting….a full tank gave about 4.5 minutes of injection which was used for about 30 seconds for take-off. A blue warning light came on at low level +- 30 seconds…inevitably as you struggled out of a confined area with high trees and no wind. As I recall the cross over from being torque limited to temp limited was about 25c at 1000 asl.

There was one expensive, albeit hilarious, incident when a tank accidentally got filled with chainsaw gas. The power and noise achieved upon system activation was impressive and the turbine section turned a nice purple colour.
Fortunately it happened at the bush camp helipad so it was an easy engine change. It was discovered upon teardown that the burner can was expanded. This led to the supposition by some that the gas lit off in the tubes before reaching the burner can. Never saw the turbine blades but according to the tech rep they weren’t pretty. The pilot said that as he rapidly shut the system off while landing he noticed the TOT gauge was pegged.

I think the 206A with the C-18 engine could be fitted with water injection but I never saw one.

Early in the 777X program, GE was considering it for the GE9X, to the point of briefing customer airlines.
It was supposed to help lower EGT in hot environments rather than increase mass air flow like it did on earlier Pratt & Whitney JT3C (707), JT9D-3AW and -7AW (747), and Rolls-Royce Spey (BAC 1-11) engines.
In the end, GE abandoned the idea as they did not have an off ramp in case the idea would not work out as hoped for.


B.

A more tragic outcome was Paninternational Flight 112 on 6 September 1971, a BAC 1-11 from Hamburg, Germany to Malaga, Spain.

Due to a maintenance mix-up, at least one of several (not properly labelled) portable containers for demineralized water that were used to fill the aircraft’s water injection system contained left-over kerosene from maintenance.
When the system activated during takeoff, both engines failed below 1000’ AGL and the aircraft landed on a motorway.
22 occupants (1 crew, 21 passengers) of the 121 did not survive the accident.

https://aviation-safety.net/wikibase/330734


B.

The SkyWest Jetstream 31s were earlier that 1990. I did a Jetstream 31 course at Prestwick in January 1984 with some guys from Sky West who were going to take the first aircraft back to Oz with them.
As an aside, most of these guys from Perth had never seen snow before, so one day we had a massive snowball fight.

Just remembered, the first Shorts SD330s with the PT6A-45A & B engines had Water Methanol injection. The later PT6A-45R engine didn't need it.

I believe the original C18B needed the water injection to get the better performance, but the later variant C18 did not. Either way it wasn't known for its excess power. And even though I don't recall any equal chainsaw gas events in my career, there was one offshore 206L I went to get that had taken off, hit the injection, then bang with an auto to the water. Everyone got out okay, but the pilot was trying to put the blame on a wrong water mix, etc. However, once the dust settled, found out he banked left over the vent stack and by sheer luck when he hit the injection button he sucked in a slug of methane.

Water Methanol Mods : Bae J31
 

Hi
When BAE did the post-mod on the J31 they modified the tail section for a small tank for WM and ran the supply lines outside the fuselage to the wing and then engines .

Dual pumps were installed and were checked before take-off ; from memory one-pump was sufficient to supply both engines (?)

At 400’ AGL the pumps were turned off because the 1st segment climb requirements had been met .

If you were judicious you got 3-4 water methanol shots out of the system .

When you turned off the water methanol you noticed and felt the noticeable drop off in performance !

We regularly operated out places with “density altitudes “ around 4000-5000’ with temperatures in Summer of over 40-44 Celsius .

Cheers
Buddy

Sport Class Air racing allows water injection:

https://www.kitplanes.com/sport-clas...rules-rewrite/

https://cimg1.ibsrv.net/gimg/pprune....6ef9cff5e7.png

LET L410 still in production.

I still remember the smell and noise when you used water alcohol injection.

Deciding to use it or not in the helicopter was a decision best made in the hover as you were supposed to lower the collective to get the temp down to 738 ( bottom edge of the Yellow Arc ) before injecting. So if you were 3/4 of the way out of a confined area with jagged rocks below and high trees ahead in the old Bung Verti-Leap 6000 with the TOT at the 810 redline and things weren’t looking good you couldn’t just flip the switch. A very speedy power reduction to 738 a flip of the switch and upward rapid collective pull were necessary. ( all, of course, done smoothly - inevitably the dreaded blue light would illuminate just to add to the fun. )
It was sometimes better to land, pick up 2-3 pax drop them off in the nearest big open area with good approaches and departure paths the go back and pick up the rest of the happy throng and the equipment, return to pick the guys up and depart to the base without using W/A at all.
Not really an option in the airline world.

The Dash 7 (certified 1978) had optional water-methanol injection. No idea if there ever was an aircraft that actually had it fitted.