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Tim Zukas
15th Nov 2022, 16:35
Do any aircraft use water injection nowadays? B-52Hs or other TF33-powered maybe?

When it was common -- when Pan Am 707s were leaving Heathrow in summer 1959, say -- how cool did the day have to be for them to do without water?

How pure did the water have to be? No dirt presumably, but was hard water okay?

CV880
15th Nov 2022, 16:42
I believe it had to be demineralized water so hard water probably no good. For the very few water injected jets at airport where I worked the water was condensate collected from heat exchangers at a nearby power station.

TURIN
15th Nov 2022, 16:50
Still some Harriers flying. Do the latest varients still use water injection?

sandringham1
15th Nov 2022, 17:26
Some Darts fitted to 748's had it but not many of those left now, the Indian built ones may still use it.

PV1
15th Nov 2022, 17:43
Some Darts fitted to 748's had it but not many of those left now, the Indian built ones may still use it.
Darts used water methanol not water, speys used demineralised water

tdracer
15th Nov 2022, 18:15
While water injection did a good job at what it was intended to do (cool the incoming air to keep peak temperatures down), it was really hard on the engine. In addition to the higher thrust settings and all the wear associated with that, the water didn't immediately atomize when injected - the impact of the water droplets deep in the compressor tended to erode the compressor blades (unlike at the inlet where the blades are designed to withstand some debris impacts, the compressor blades deep in the compressor assume all the nasty stuff has evaporated or been centrifuged out and are relatively fragile).
Very important to use reasonably pure water (demineralized or distilled) to avoid mineral deposits on the compressor blades - really messes up the aerodynamics of the blades, plus large deposits can shed causing downstream damage.

treadigraph
15th Nov 2022, 18:22
I remember seeing a USAF EC-135H performing a very sprightly take off during a show at Mildenhall and the commentator (Airsound?) remarking on something being injected, but whether it was water or methanol I can't recall - there was an interesting moment at about 200' when some combustion could be seen and heard - "added son et lumiere" said our man on the mic... Might have been compressor stalls as I recall it pitched up a fair bit! Long time ago tho, J57 or TF33s, did they ever get modified with CFM-56s?

Wasn't the 707 known by some as the Water Wagon?

Compass Call
15th Nov 2022, 21:02
I thought that jet engines with water injection had the water injected into the combustion chambers. This was to cool them to allow more fuel to be injected to increase the power output.
Turboprop engines with water-methanol injection had the water-methanol injected into the compressor to restore the power output.

If you make a mistake and use water-methanol on a pure jet engine you end up destroying the turbine blades, as happened to a BAC 1-11.

tdracer
15th Nov 2022, 22:47
Treadigraph, all KC-135s have been re-engined (at least the ones still flying) so I don't think water injection is still a thing for that aircraft.
Compass - at least the engines I was familiar with, injection occurred mid-compressor. Cooling the incoming air has an additional advantage of improving compressor performance while lowering the peak EGT so you don't melt the turbine.

dixi188
15th Nov 2022, 22:57
I thought that jet engines with water injection had the water injected into the combustion chambers. This was to cool them to allow more fuel to be injected to increase the power output.
Turboprop engines with water-methanol injection had the water-methanol injected into the compressor to restore the power output.

If you make a mistake and use water-methanol on a pure jet engine you end up destroying the turbine blades, as happened to a BAC 1-11.
I don't recall a WaterMeth incident with a BAC1-11 but the PanInternational accident at Hamburg was caused by Jet A1 being added to the De-Min water tank.

Afrijet
15th Nov 2022, 23:03
Metro Liners still use it. So do some guys with turbo Buicks with 3.8s and gmc typhoons. Usually a water/methanol setup. Same idea though. FYI, not all kc-135s have been converted to cfms. Some still use the smokers as do e-3s and other airframe derivatives of the kc.

CaptW5
15th Nov 2022, 23:42
It has been a long time , but we used water methanol (ADI, anti-detonation injection) on the R-2800-CB16/17 on the Convair 440 and the DC 6.
I also recall using water methanol on the Darts on the Viscount 806X and the Convair 640. The Convair 580's that were with Frontier also had water methanol injection. We leased a couple of them, and they were different in that regard.

Most of the time we had barrels of water methanol available, but if there wasn't any we used straight water. It nede a flush afterwards.

I have heard of incidents with the Darts were the wrong fluid was used (in one case jet fuel, in another Varsol cleaning fluid); resulting in dual engine failures on take off.

tdracer
16th Nov 2022, 00:01
Metro Liners still use it. So do some guys with turbo Buicks with 3.8s and gmc typhoons. Usually a water/methanol setup. Same idea though. FYI, not all kc-135s have been converted to cfms. Some still use the smokers as do e-3s and other airframe derivatives of the kc.
Those don't have the original pure jet TF-33s. They were re-engined with JT3D low bypass turbofans (salvaged from scrapped 707's) back in the 1980s (there was a plan to update those to CFMs as well but it may well have been cancelled). The USAF E-3s were built with JT3Ds (NATO got CFMs on the original build). I'm pretty sure they're not equipped with water injection.

treadigraph
16th Nov 2022, 02:30
Treadigraph, all KC-135s have been re-engined (at least the ones still flying) so I don't think water injection is still a thing for that aircraft.

This was early 1980s I should think, I don't believe I attended the Mildenhall shows after 1987 or 88. Definitely not a CFM equipped aircraft.

Senior Pilot
16th Nov 2022, 02:31
The C20B powered Bell LongRanger 206L is water methanol injection capable, used when power limited and gives a useful 50-80*C drop in TOT (IIRC) with corresponding increase in torque available.

Certainly reduced the need for Comp Washes when I flew one, but pure water/meth essential as already mentioned: not many around these days, though 👍

Anilv
16th Nov 2022, 03:24
Last encountered them when I did a loadsheet course for SAA around the late 80s I think. It was explained that there was big tank which would be emptied during the take off. Tank was in the wingbox area as had an open top as a closed tank would not allow the pumps to flow as fast. I seem to remember the figure of 3000kgs added if water injection was used but it was a long time ago.

Anilv

Quietplease
16th Nov 2022, 09:03
All water injection did for a BAC1-11 was make it noisier. No discernible effect on performance.

Mogwi
16th Nov 2022, 09:11
The Pegasus engine in the Harrier (all versions) did indeed use demin water injection. It had 50 gallons (proper ones) and lasted c 90 secs (or c 3 mins with half flow mod), giving an extra 1500 lbs of thrust. Extremely useful in hot/high conditions as it reduced the JPT considerably for given rpm. I used to give a quick blip as the jet ran up the ramp (for mum!) which left loads for subsequent landing.

Very useful in the Farley Climb as the JPT could otherwise get pretty high with high rpm and low forward speed. It made the exhaust quite smoky and that was a bit of a give-away in a low-speed fight 😊

it was fun to turn up at a display and when asked how much fuel you needed, reply “Fine for gas thanks, just give me 50 galls of water!”

Mog

longer ron
16th Nov 2022, 09:36
it was fun to turn up at a display and when asked how much fuel you needed, reply Fine for gas thanks, just give me 50 galls of water!

Mog

Indeed Mogwi :)
At our final? Dunsfold Families Day the RAF kindly supplied 2 x GR7's for a display flight (Jenks ?).
We usually had 2 x Demin Bowsers - one with electric powered pump (for hangar) - the other with a single cyl Yanmar diesel for the flightline.
Meanwhile the diesel bowser had been sent 'oop north' without anybody telling us (situation normal then :) )
Anyway the 2 GR's arrived and requested water I said '' leave it with me'' and we went and collected as many extension reels/leads as possible - now I cannot remember exactly how far the a/c was from the flight line hut but it must have been 100/150 yards LOL - the electric bowser slowly filled up the tanks with us keeping a close eye on the ext leads,we didn't see any smoke :) but it took a while !

Alan Baker
16th Nov 2022, 10:08
Those don't have the original pure jet TF-33s. They were re-engined with JT3D low bypass turbofans (salvaged from scrapped 707's) back in the 1980s (there was a plan to update those to CFMs as well but it may well have been cancelled). The USAF E-3s were built with JT3Ds (NATO got CFMs on the original build). I'm pretty sure they're not equipped with water injection.
TF33 is the military designation for the JT3D. The original pure jet engine was the J57.

ZFT
16th Nov 2022, 10:45
Last encountered them when I did a loadsheet course for SAA around the late 80s I think. It was explained that there was big tank which would be emptied during the take off. Tank was in the wingbox area as had an open top as a closed tank would not allow the pumps to flow as fast. I seem to remember the figure of 3000kgs added if water injection was used but it was a long time ago.

Anilv
From an aged memory at SAA in the 70s the B707B/C was 334000 lbs dry, 336000 lbs wet max take off so 2000 lbs water? Good for about 2 mins

teeteringhead
16th Nov 2022, 11:16
Had water-meth injection on a Jet Ranger I flew in the Middle East - gosh - nearly 50 yers ago. Some days I reckon we could have used more water-meth than fuel.............

dixi188
16th Nov 2022, 11:39
All water injection did for a BAC1-11 was make it noisier. No discernible effect on performance.
IIRC the water injection gave another 500lbs of thrust below 25C and restored thrust when hotter up to about 40C.
Used on most take offs in Oman.
I remember going out of Tehran in 1979, (me on jumpseat), the water ran out as we hit the inversion layer. The aircraft stopped climbing until we got a good distance from the city. The Captain wrote in the F700, (tech log), Max Continuous Thrust used for 17 mins. The answer "Noted with thanks".

stevef
16th Nov 2022, 16:45
There's an interesting photo of an Emerald Airways HS748 (G-ATMJ) with an engine on fire during ground runs. The rumour was that waste Avtur had been drained into a water meth drum at some time and later unknowingly decanted into the aircraft's water meth tank. :eek:

Compass Call
16th Nov 2022, 19:06
When a 1-11 took off without using water, it was like a 'Smokey Joe', trailing smoke into the distance.
When it used water, there was no smoke, just extra noise.

Flightrider
16th Nov 2022, 23:18
Monarch and Dan-Air ended up with a fairly major logistical operation to make sure barrels of de-min water were properly marked and positioned at airports around the network where they were required for the performance enhancement. The marking of the barrels was much clearer after the Paninternational accident mentioned earlier, when the de-min water tanks were accidentally filled with JetA1 with dire consequences.

Hand-pumping the stuff into the aircraft was generally the F/O's job on turnround unless you could "induce" a rampie into doing it. Unless I'm much mistaken, the BA 1-11-510EDs didn't have the capability and it fell into disuse during the latter days of the type's service even on the 517FE and 518FG aircraft with Dan-Air and British World, and the ex-BCAL aircraft that ended up with European Air Charter via BA.

I do recall standing not too far behind a Tarom 1-11 operating for Adria Airways in about 1985 and getting a little bit wet as the water at the very beginning of the take-off roll was simply ejected downwards and backwards from the aircraft onto a pathway below the runway. The "extra noise" probably explains why I'm having increasingly frequent arguments nowadays with the other half about being a deaf old git...

stilton
17th Nov 2022, 04:02
I believe the Jetstream 31 also used water methanol when necessary

Anilv
17th Nov 2022, 04:37
From an aged memory at SAA in the 70s the B707B/C was 334000 lbs dry, 336000 lbs wet max take off so 2000 lbs water? Good for about 2 mins

Forgot to mention my experience was on a 747.

cheers!

bean
17th Nov 2022, 05:24
When a 1-11 took off without using water, it was like a 'Smokey Joe', trailing smoke into the distance.
When it used water, there was no smoke, just extra noise.
Other way round

India Four Two
17th Nov 2022, 06:34
Just so the younger folk know what we are talking about, here's an AA 707 leaving LAX. It looks like they have raised the gear to clear the fence!


https://cimg0.ibsrv.net/gimg/pprune.org-vbulletin/1024x602/707_smoke_0fba398cfbeab4f8e7cff175cc421777883c41aa.jpg

ZFT
17th Nov 2022, 06:41
Forgot to mention my experience was on a 747.

cheers!
I had completely forgotten the SAA 747s initially operated with water injection.

dixi188
17th Nov 2022, 07:35
Water injection flow rates on the BAC 1-11.
The water tank held 110, (1100 lbs),imp gallons and this was used up in around 2 mins. so thats around 275 lb/min per engine. The take off fuel flow would be around 10000lb/hr which is 166lb/min. Therefore the water flow was a lot higher than the fuel flow. I always though this a bit incongruous.

Smokey engines. Am I right in thinking that JP4, (Wide Cut Gasolene), caused a lot more smoke than JET-A1, (Kerosene)?

Other aircraft with water/methanol injection include the early Shorts 3-30s with the PT6A-45A and B engines and anything with the RR Dart.

How can I remember all this stuff yet don't know what day of the week it is, I put the bins out on Monday instead of Tuesday.:)

safetypee
17th Nov 2022, 11:08
https://cimg4.ibsrv.net/gimg/pprune.org-vbulletin/705x401/1_fdc580ac3e27526f34216496ebcacf9c7730f8d7.jpg

Ref #25

The conclusion was that it wasn't water meth in the water meth tank

ETOPS
17th Nov 2022, 15:05
Flightrider

Unless I'm much mistaken, the BA 1-11-510EDs didn't have the capability

Thats correct - resulted in much fun trying to explain to various European ATC towers why we would be effectively orbiting during the departure to get to MSA before setting course!

PS How the heck has this triggered memories of all the power settings/call outs?

vegassun
18th Nov 2022, 13:26
I believe the Jetstream 31 also used water methanol when necessary
It did indeed. IIRC you could get three T/Os out of the tank if you used it sparingly.

Aeroservice
18th Nov 2022, 15:50
I had completely forgotten the SAA 747s initially operated with water injection.

Yes the early S.A.A. B747's coming in and out of Heathrow were looked after by those of us on the BOAC, then B.A. Foreign Ops Team. We were often called to fix the Water injection System.
The P&W JT9D's needed a little help getting full power during hot or high Ops.
The Water Injection system had a Tank in the Dry Bay, forward of the Centre Fuel Tank. High-Capacity Electric Pumps were located in the L/H and R/H Inboard L/E Edge Area.
Tank was topped up to full with De-Min water. We had a Bowser at Heathrow specially for Demineralised Water. Probably left over from the B707's..
Water Injection was selected and armed from the F.E.'s Panel from memory and the system would run at full bore when initiated with the 3 phase Pumps activated by the Thrust Levers position, almost at T/O Power, until the Tanks were drained.
Water was introduced into the Compressor front end and would apparently increase the density of the air going through the Engine to give it a little power margin at hot or high Airfields.
The Crews we talked to said it helped a little but wasn't really that effective and was a tad unreliable.
I remember when we used to function the system after repairing it, the function would be noticeable with electrical power draw on the APU or GPU and you had to be careful with it.
Hope that helps...

wrecker
18th Nov 2022, 16:53
The Spey 512W fitted to the HS Trident 2E had water injection.

blind pew
18th Nov 2022, 17:26
And it generally ran out below 500ft..Tel Aviv we had to cross the coast above 1,000ft due to the military patrolling the beach watching out for terrorists.Of course it was rare to reach 1,000ft as we hit the inversion which put paid to a reasonable climb rate especially as we had the good old whip the flaps up at 90 seconds and reduce the power to Noise abatement setting which was below climb power.

Allan Lupton
18th Nov 2022, 21:12
The Spey 512W fitted to the HS Trident 2E had water injection.
Yes, on the Trident we only used water injection for take-off, 1st and 2nd segments so could use demineralised water, rather than water-methanol. One-Elevens could use water for Approach climb compliance so had to use methanol as anti-freeze to cope with the cold during cruise.

dixi188
19th Nov 2022, 11:52
Yes, on the Trident we only used water injection for take-off, 1st and 2nd segments so could use demineralised water, rather than water-methanol. One-Elevens could use water for Approach climb compliance so had to use methanol as anti-freeze to cope with the cold during cruise.
I don't remember any methanol on the 1-11. There was a mod. to heat the water tank so the water could be carried to destination. ISTR that without the heater the water had to be dumped after 1 hour to avoid freezing. The tank was at the front of the aft baggage hold so not exposed to extreme cold.

Rick777
19th Nov 2022, 20:36
I flew the KC 135 from 1974 to 1988. The A model carried 2000 lbs of demineralized water that lasted about 2 minutes on takeoff which usually got us up to 500 feet or so if heavy and 2000 feet if light. It could be used down to 40 degrees F. It gave a little over 1000 lbs of thrust per engine which is needed when the engine only puts out a little over 12,000 lbs for a 297,000 lb airplane. The R model's CFM 56 put out 22,000 lbs. We were like kids with a new toy. The E models were re-engined with JT3Ds that put out 18,000 lbs of thrust so they didn't need water injection. I only really know about the tanker versions of the plane.

megan
20th Nov 2022, 02:25
Rick, I read that each wing had one water pump to feed both engines on that wing, so pump failure meant loss of thrust on both that wings engines. Systems can make life interesting.

Jeremy Hassell
23rd Nov 2022, 19:18
I wish I could remember which aircraft my late father worked on at Wisley, Surrey, during the 1960s. He was Technical Director for Elga Products Ltd as a pioneer and took Demineralisation cartridges along with him to trial high quality water in their aircraft engines. They proved highly successful.

CV880
29th Nov 2022, 21:33
Since several posters brought up water injected JT9s on some 747s I have a few comments.

Contrary to some above posts the water was injected into the combustion liner via the fuel nozzles.

There were two water tank configurations. 747-100s utilised the dry bay in the centre wing box between the front spar and 1st spanwise rib. The dry bay did not exist on 747-200s so there were 2 tanks, 1 in each inboard wing leading edge.

Injecting water into the combustion liner caused a thermal shock and metal fatigue and eventually there were instances of the combustion outer case rupturing on take off which blew the cowlings off along with other damage.

Filling the demin water tank took quite some time as you had the honey truck servicing the mid lavs, the potable water truck and the demin water truck all trying to get in the same area along with a catering truck at door 2R. On a quick turnaround it was not uncommon to be still pumping demin water in almost up to pushback, the demin water truck usually being the last to get access.

The 2 operators of water injected 747s I was familiar with appeared to use the water to lower the EGT in an attempt to prolong the hot section life of the -3A engine. They did not use it for the extra thrust and given the sector lengths they were flying from my location could even have used a derated thrust most of the time. I seem to recall they used water whenever the OAT was above something like 24C. One of the operators only filled the water tank to about 2/3rds of full.

I have a distant memories of a trans Pacific operator of very early 747-100s who started to retrofit the water injection system instead of upgrading their -3A engines to -7CNs (which nearly everyone else did) but quickly changed course and abandoned the water retrofit and upgraded the engines instead. I have memories of seeing at least 1 or 2 of their older aircraft with all the water control panels fitted but inactive (it was over 45 years ago so memory might be playing tricks!!)

rog747
10th Dec 2022, 12:19
Sad case of Paninternational BAC 1-11 500 D-ALAR Flight 112 that force landed after take off and crashed on the Bundesautobahn 7 highway near Hamburg Airport Germany, killing 22 of the 121 on board on September 6, 1971.The BAC 1-11 had both engines fail on take-off.
The flight was enroute from Hannover via Hamburg to Malaga Spain.
The Investigation revealed the engine's Water Injection system tanks were inadvertently filled with Jet fuel Kerosene causing an overheat and seizure of both engines.
This was due to a handling and filling error the night before at Dusseldorf of the five water canisters.

HAMBURG AIR DISASTER British Movietone News

While on the ground during the stop at Hamburg, the five water canisters were offloaded from the cargo hold.
The canisters should have contained demineralized water and were used to fill the engine's water tank giving better engine performance during the takeoff.
Manfred Rhode, co-pilot of the "D-ALAR" (975 flight hours), unsuspectingly pumped the contents of all five canisters into the water system of the BAC 1-11.

The airplane was prepared for the next flight to Mlaga, taxi clearance was given to runway 34. Take off was commenced at 18:18.
The Captain had opted for a takeoff with water injection in view of the high ambient air temperature and their actual take-off weight for the full flight with enough fuel needed for Malaga.
Reaching a speed of V1 during takeoff, the crew noted a sharp rise in EGT.
Takeoff was continued and 2 loud bangs were heard.
The left-hand engine had failed, immediately followed by the right-hand Rolls Royce Spey engine.
The airplane was barely climbing through an altitude of 250m and the pilot pushed the nose down to gain speed.
The engines were not producing power forcing the crew to carry out an immediate emergency forced landing on the Hamburg-Kiel Autobahn E45 just 96 seconds after take off.
Due to the high sink rate the BAC 1-11 500 Jet touched down hard at over 200kmph.
The left hand main gear collapsed. The crew applied brakes to try to keep the airplane on the road.
The left wing and tailplane then struck concrete pillars of an overpass, causing the flight deck to break off and separate. The fuselage skidded and broke up, bursting into flames.
Men from the Hasloh volunteer Fire Brigade are the first to help at the scene of the accident, alarmed by the loud bang on the Autobahn.
When they arrive, it looks like a battlefield. "Shoes and bags, burst suitcases and mountains of luggage lay between countless pieces of wreckage strewn along the roadway."
The female first officer of the flight, Elisabeth Friske survived the accident. She sadly later died in a Cessna Citation accident on May 31, 1987.
99 of those on board miraculously survive the accident and the pilot and his two co-pilots survive in the torn-off cockpit.
Co-pilot Elisabeth Friske has a broken leg and is in shock. As firefighters try to free her from the cockpit, she says there's no way she'll leave the plane without the pretty sandals she had just brought back from Egypt. A fireman remonstrates with her, after which she lets herself be freed from the wreckage.

Investigation revealed that two of the five water canisters actually contained kerosene.
The canisters had been mishandled at Dsseldorf the night before and were then loaded on board the plane.
At the Investigation F/O Rhode denied not to have heard a warning from the loader Karsten Henneicke ("It stinks of fuel here") But Henneicke claims that Rhode replied: "Everything stinks of fuel here.''


https://cimg9.ibsrv.net/gimg/pprune.org-vbulletin/600x431/241526740_1846815842193363_8702738567057901666_n_08232dd9f94 3ff1eba1cd62e2f64b9a5c63dde56.jpg

Crew Photo: "Before the unfortunate flight on that day''.
Captain Reinhold Hls (left) and the co-pilots Elisabeth Friske and Manfred Rhode with D-ALAR.

rog747
10th Dec 2022, 13:41
The day when a Boeing 747 almost crashed on downtown Athens, SX-OAA, named Olympic Zeus,
The Captain Who Broke The Rules and saved 418 Lives (398 pax and 20 crew)

Olympic Airways 747 almost crash Athens 1974 (https://greekreporter.com/2022/01/20/olympic-airways-crash-athens/)

Flying from ATH to JFK in August 1974 during the take off run on a typically hot Athens summers day the 747 was using water to assist the engines with extra thrust when a loud bang was heard but the Captain elected to continue the take off.
The aircraft just cleared the boundary fence and then against the Company rules Captain Migadis elected to raise the gear.
He then traded some 50' of height for more speed.
He thought well, we were all dead, it's over. The aircraft was carrying 160 tons of fuel, as it would fly directly from Athens to New York.
In the main cabin Cabin Crew member Lucia Siachou got an intercom call from a colleague seated right at the back who had seen engine number three on the right hand side had blown up. The colleague said “we are screwed” and she just replied with “I Know”.
Controllers in the tower watched on in horror as they watched the plane struggle to gain altitude heading towards the City.
The Captain's reasoning for raising the gear was that he needed speed in the long term, he had a hill in his flight path and there was no way that he'd be able to clear the hill with the gear down slowing the plane down.
He was relying on his decades of experience and so he made the call.
The controllers watched as the plane barely gained any more altitude once the gear was up but soon the plane gained a bit of height, probably whilst still in Ground Effect.
But the 200 foot tall Panos hill was now barely a mile away. The captain did not have a choice; he pulled the nose up as the airspeed he had built up so far bled away.
The 747 Jumbo Jet cleared the hill by 9 feet.
But this was far from over, climbing to avoid the hill had cost him precious airspeed. He now had to drop the nose again to speed up otherwise the jumbo jet would drop out of the sky.
The captain decided to trade more altitude for about 6 knots in airspeed. It wasn't much but it would keep them from stalling.
At this point the jet was still so low that it barely cleared cleared some Radio and TV antennas.
But little by little Captain Migadis in his 747 managed to gain more height and speed and so then slowly turned and headed out over the sea where the air temperature dropped a little thus gaining even more height.

The crew barely able to keep the plane airborne, had been flying just 200 feet above a densely populated area of Athens. Airspeed was exceptionally slow, the FDR showing as low as 158 kts, which was not possible according to Boeing.
Later attempts in the Simulators would result in crashes at every attempt to recreate the same flight pattern.

After almost two minutes flying straight and as low barely 50m above the ground the captain was able to gain some airspeed and finally altitude up to 1,500ft over the sea.
After quickly dumping fuel over the water, the plane landed safely back at Ellinkon, some 30 minutes after takeoff.

It was discovered that the #3 engine's water injection system was mistakenly turned off prior/during takeoff, causing the engine to overheat and explode during rotation.
The water injection for engine #3 was switched to 'On' during the ground checks, but the F/E inadvertently switched it 'Off' before or during the take off.

There was a very complicated water injection system that could be used with the following early JT9D engines on the 747 :
JT9D-3A, Dry T/O rating 43.500 lbs. Wet rating 45.000 lbs.
JT9D-7 and -7H, Dry T/O rating 45.500 lbs. Wet rating 47.000 lbs.
JT9D-7A and 7AH, Dry T/O rating 46.150 lbs. Wet rating 47.670 lbs.
JT9D-7F, Dry T/O rating 46.750 lbs. Wet rating 48.650 lbs.

Water alone is specified and should contain no more than 10 (ppm) parts per million impurities.
Use of water is limited to takeoff operation up to an altitude of 8,000 feet at the minimum ambient temperatures of 32F.
Take off using water injection at max takeoff power is limited to a maximum period of 5 minutes including operation with water injection for not more than 2 1/2 minutes

On the 747-100/200 two water tanks were each built in the wing roots (left and right) and extra piping was installed for transportation of the water to the four engines (one tank for 2 engines at the same wing.) Also piping for water filling and draining of residual water after T/O was installed.
Four high capacity water pumps were feeding the engines with water.
Each engine had an adapted fuel control to cater for extra fuel when the system was activated.

System operation (747)
- When a wet rating was needed min. 2300 kgs of water was uplifted. (standpipe level was 2450 kgs)
- During Taxi-out, just before entering the runway, the system was switched on (F/E panel), the four water pumps were momentarily giving a flow indication (four green lights), check all water low press lights out. Most frequent failure at this moment : water pumps start to operate but the water shut off vlv is still (partly) open. This is called a "steam out".
The relevant engine (still at idle) gets the full water flow and stops operating and has to be restarted, after switching off the water injection system.

When entering the runway the system is now armed.
After advancing the powerlevers at approx. 1.25 EPR the system comes in, four green water flow lights illum (pilots annunciator panel), the water shutoff valves are open.
Careful monitoring of the EGT indication is crucial (one engine can suddenly revert to no water (pump failure), but still with the high (wet) fuelsetting.
After 2.30 minutes or just before water run out (indicators on F/E panel), the system is switched off.
Switching off was the most tricky part of the operation, because of the low usage of the system frequently failures occurred.
The most dangerous was that the water pumps stopped and shut off valves closed but one engine fuel control stayed at the wet fuel rating.
Before you could blink an eye the EGT exceeded the T/O limits and an expensive horoscope check or even an engine change was required.

From a KLM friends 747 crew perspective - Wet Take Offs between 1978 and 1990 on KLM 747-206B aircraft.
Most of them on the AMS-LAX NBO-AMS and AMS-IAH stretches, nearly always air-conditioning packs switched off enables more thrust from the engines.
All three of us in the cockpit were always fully aware that in fact this aircraft was underpowered when at MTOW, and the engines required a lot of extra attention during these kind of Take Offs plus at Hot and High airfields.
The engine sound of the 4 P&W JT9D-7W changed to a very low growling sound when the water injection came in at approx. 1.25 EPR powersetting. Most of the time we left the brakes on a little longer as so to gain some runway length and checked that all four green waterflow lights were illuminated.
After the"Water on" call the brakes were released.
With four growling engines it took a very long time before Vr was reached. It always looked very close to the end of the runway.
Slowly climbing with mostly MTOW (351.000 lbs) we climbed away until the water was almost running out or 2.30 minutes was reached.
Now "water off" was called by the F/E to warn us pilots for the impending thrust decrease.
Power levers were retarded a little bit, before actual stopping of the water injection system on the F/E Panel.
This was done to prevent an overboost during transition to the Dry setting.
Now GA or CLB was selected at the engine mode select panel and depending climb out procedures, GA or CLB thrust was set.
Especially after selecting the 'water injection off' and setting CLB thrust it became very quiet in the aircraft, so sometimes the captain warned the passengers before take off, that after take off the engines were only retarded and had not stopped!
KLM 747's at first had the -3AW engines but these were changed to -7W or -7AW.

I gather that also the Northwest Airlines DC-10 series 20 (as it was actually known, but monkiered as the -40 series) were fitted with PW JT9D-20/20J engines that would come with water injection and all of these DC-10 -20's were equipped with water injection and were certified with the water injection system working. The aircraft were "never" operated AFAIK in service using the water injection.
Both the JT9-20, and -20J had been equipped with water injection but this was removed later on to save weight.
At first some of the aircraft water injection lines were removed to ease maintenance in the LH wheel well, the wing leading edges, and the engine pylons in the early 1980s.
The rest of the system was removed, other than the tank, in the early 1990s.
The water tank is mounted on the lower LH side of the fuselage, just aft of the wing, and looks like a body fairing. The drain mast for the tank is just below the aft or bulk cargo door, just left of the centerline of the belly. The tank held 600 gallons of demineralized water. There were three pumps located in the tank.
The only parts of the water injection system that were left on the engines were the fuel nozzles with the water injection ports capped off.
There was never a ' W' in the engine's designation on the data plates for either engine.
The JT9-20 was a JT9-7A that was adapted for the Douglas application, which means that the gearbox was mounted under the fan case.
The JT9-20 had a takeoff EPR of 1.46, and put out somewhere in the neighborhood of 44,000 lbs dry thrust, without water.
The JT9-20J was a JT9-7F, that had the turbine section out of the -7J, and a different fuel pump than a -20.
This engine had a takeoff EPR of 1.51, and put out roughly 48,000 lbs of thrust dry, or without water.
The -20J had a higher max EGT limit than the -20.
These two engines side by side were basically identical.
All of NWA DC-10-40s were certified at 535,000 lbs gross weight, so a -20J powered aircraft simply had more power and these aircraft were used on different routes.
In the mid 1980s P&W offered to convert the NWA DC-10-40s to JT9-7R4 power, like they did at JAL, but the aircraft was being looked at for retirement at that time, so they passed on the offer, but the NWA -40s actually stayed on for another 18 years or so.

The NWA DC-10-40s were actually DC-10-20s...Donald Nyrop, who was the CEO at the time had ordered his DC10s with the JT9s and the extended range upper and lower auxiliary fuel tanks, longer wingspan, center gear, and so on.
He then found out that Douglas was going to hang CF6-50 engines off of the same airframe, and call it a DC-10-30, well he flipped out and basically demanded that his P&W powered DC-10s be re-designated as -40s...He wanted to have the higher number, not to be outdone by the new and higher numbered -30s that would follow and show the World he had the 'better' DC-10.

While working on the DC-10-40, one would find numerous bookwork and data plates on parts of the aircraft that pertained to the P&W application, and they would be stamped DC-10-20.
The upper and lower auxiliary fuel tank access panels were also stamped "DC-10-20/-30 only".

cavuman1
10th Dec 2022, 15:46
Very informative post, rog747! Thank you for taking the time.

- Ed

mustafagander
11th Dec 2022, 10:02
Thanks for the info rog747.
I operated B747-238 with P&W JT9-7AW engines. These aircraft used 2400Kg water, 600Kg per engine for 2.5 minutes on takeoff. We FEOs checked the gauges carefully coz we needed the lot.
There was only ONE water pump switch on the FE panel fwd knee panel for all pumps along with the lights as described. Of that I am absolutely certain, definitely no individual pump switches.
As I recall it the water tanks were plumbed such that one tank fed inboards and the other fed outboards. It was also necessary to ensure that Galley Power was switched off after start prior to using water coz the AC system could not support the load if the GP did not automatically switch off when Water On selected.
Calculating performance data for a wet takeoff was an absolute nightmare. Three of us would fish the numbers out of our performance manual independently and regularly came up with three different answers usually 3-4 tons MTOW difference. It mattered when we were operating PER-BOM return and BKK-ATH return coz every Kg of fuel was needed and we had lots of cargo offered.
Ah the Good Old Days!!