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ADA AW139 Ditched?

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ADA AW139 Ditched?

Old 7th May 2017, 04:46
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Tell us all, oh great, all knowing, Sultan?

What exactly IS a 235?
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Old 7th May 2017, 07:25
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Apate - I did say "as far as I know' - The S76D RFM is one I have never had the privilege of reviewing. So in that case, I wind my neck in. By way of a word of caution I would differentiate between the RFM and your company ECL. The former - certainly in that part of the past I am familiar with - put an obligation upon the pilot to accept the fire warning as gospel. Some aircraft (S92?, Super Puma series?) have such a poor record in this respect that it would be unusual if the company ECL did not reflect this. There are some societies where absolute adherence to the book is a given and the lack of any room to avoid arriving at the last line in the drill that invites LAND IMMEDIATELY is problematic.

Yes, the 139 system is pretty reliable but I know from an analysis of over 1500 incident reports relating to the 139 that the three fire warning related incidents were all non-events.

We find that those entering the complex world of the latest generation of helicopters for the first time encounter a problem caused the relative scarcity of (serious) system failures.

Managing over and under reaction is an important element of airmanship. That's why Evidence Based Training using scenario type exercises and properly trained sim instructors has a lot to offer our industry.

The guys in AD did the right thing and I would venture to suggest that this was in no small part down to their (apparently) high level of experience.
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Old 7th May 2017, 09:34
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Originally Posted by Geoffersincornwall
...The guys in AD did the right thing and I would venture to suggest that this was in no small part down to their (apparently) high level of experience.
If a crew with high level experience has followed a checklist to its end point I should hope that the final outcome would be no different to that of a low experience crew faced with the same circumstances following the same checklist.
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Old 7th May 2017, 10:54
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Originally Posted by The Sultan
212man wrote relative to 92 fire warnings:

Then you are saying that the Cougar crew acted with proper airmanship as they relied on Sikorsky propaganda about the 92's 30 minute loss of lube lie instead of following the RFM to the letter. This from you who parked a 92 1 km short of an airfield because of a (later determined) non-event oil pump failure. There you had a safe place to land once you mis-interpreted the criticality of the situation and decided to follow the RFM instead of using airmanship to stay in the air another 60 seconds.

After the second false fire warning the 92 should have been grounded like the 235 after the oil pump drive gear failures which in the end were as serious as the 92 pump failures (which did not result in grounding). The 235 crews showed they were pros by following the RFM to ditch after an erroneous second failure indication said they had backup lube failure, which was caused by gross incompetence by Airbus wiring the sensor backwards. They could have made it to a dry landing, but thought of their passengers instead of future bar roomy war stories.
You've written some bollocks in your time but this one takes some beating!

I did not have a pump failure and have never said that. What I did have was a cabin full of smoke and the smell of being in a welding workshop, plus 9 EICAS captions. We were not following any RFM procedure and were not 1km from the airfield (although quite close).

I have never supported the Cougar 491 crew actions and think the 30 minute issue was never in their thoughts and is a red herring.

The 225 Emergency Lube sensors were not 'wired backwards' (although there was a change in pin selection) and the primary issue was the pressure thresholds being too high.
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Old 7th May 2017, 10:55
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I seem to remember that the BO105 had an air pressure switch to indicate a fan drive failure. A simple system to give the pilot cockpit information about the fans condition.
The reason being that originally there was no ram air for the coolers (engine and gearbox).
The aircraft was modified to provide a ram air system.

The 139 MRGB has no ram air system (the engine oil systems being fuel cooled). The 139 is not alone in this respect. It seems a little extreme to loose an aircraft for the want of air when it is passing by at 100+ knots.

Last edited by ericferret; 7th May 2017 at 11:07.
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Old 7th May 2017, 11:08
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I don't think cooling is the issue, and the MGB will run quite happily much hotter than in this incident. The issue is the sound of mechanical distress and the uncertainty about what its cause is.
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Old 7th May 2017, 11:20
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Yes I am sure you are right. Nothing to say that any fan fail (in general) was due to an internal gearbox failure as opposed to a simple fan failure.
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Old 5th Jun 2017, 05:57
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What is the nominal operating tempurature...

For the AW139 main transmission?
The system has an 82c thermostat, so in a sufficiently well-designed system, shouldn't this temp be maintained in normal S&L flight conditions?

The same oil is used in both the engines and the transmission, yet the engines are ''red-lined'' @ 140c and the transmission @ 110c...
.....Reasons?

Someone mentioned the engines having a fuel-cooled oil cooler....this is more of a heat exchanger with the primary purpose of heating the fuel, it does little, or nothing to cool the engine oil. The engine oil temps (in hot climates) run at around 115 to 125c ....and during the two minute cool down after flight can often reach 140c!
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Old 5th Jun 2017, 13:38
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I had an MGB "Warning, Warning" Oil Temp event in a 139, (reported within company and national system). It was accompanied by an increasing MGB Oil Temp all the way to landing with the highest temp noted by myself at 137c. Of course it happened over water about 11nm from the coast, of course I followed RFM actions however, I briefed the crew to prepare to ditch and gave the ditching plan to all onboard. Whilst, stating that under current situations (normal pressure, no noise or vibration) that we would only ditch if we received secondary indications (vibrations/noise). Altitude was decreased to 200-300 ft over water and speed reduced (all gradually so as to not excite an already excited MGB),

A pan was also declared to ATC and intentions for arrival if we made feet dry (coastal airport). Fortunately, we had no secondary indications however, we were prepared to ditch 50m from shore or Land immediately in the trees short of the strip, if secondary indications presented themselves.

A dynamic situation, and though we suspected a cooling system issue, we didn't know for sure.

My point of this diatribe is; well done to the crew with ADA, they are all alive. Every situation is different yet, they made the tough decision to ditch based upon their situation. I, personally, am grateful for their decision and also believe that the fact they are all still breathing, support it.
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Old 5th Jun 2017, 13:49
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I absolutely agree...i guess i would have run through the same thought process you did-and deciding to ditch when you are close to the shore is probably one of the toughest decisions one has to make-ever.

The outcome is what proofed them right....all came out alive and unharmed.....
 
Old 5th Jun 2017, 14:51
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Sid447, the Fuel Cooled Oil Cooler is just that, an oil cooler. There is a separate Fuel Heater for heating the fuel. It just happens to use engine oil for heating the fuel

Oil is also cooled by intake air, as the oil tank in the Accessory section has fins that intake air passes over, helping to cool the oil.

Temp limits are not to do with the oil, they are a function of the temp limits of internal components in the engine or gearbox. The oil will not begin to break down until it gets much hotter than the MGB temp limits, but the components are always much hotter than the oil (the oil only carries some of the heat away).

There have been coking issues with some engines, particularly running 2380 oil in high temp locations. The Turbine Scavenge Pump especially was heat soaking after shutdown causing the oil to coke up.

Originally Posted by Sid447
What is the nominal operating tempurature...

For the AW139 main transmission?
The system has an 82c thermostat, so in a sufficiently well-designed system, shouldn't this temp be maintained in normal S&L flight conditions?

The same oil is used in both the engines and the transmission, yet the engines are ''red-lined'' @ 140c and the transmission @ 110c...
.....Reasons?

Someone mentioned the engines having a fuel-cooled oil cooler....this is more of a heat exchanger with the primary purpose of heating the fuel, it does little, or nothing to cool the engine oil. The engine oil temps (in hot climates) run at around 115 to 125c ....and during the two minute cool down after flight can often reach 140c!
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Old 6th Jun 2017, 11:15
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Thanks ''nooby''

appreciate the input.
Though have to say, the engine oil coolers are pretty ineffective.

Still asking for someone to give me some insight on nominal MGB temp.
We had a box change on one of our 139's about 18 months ago and that one never goes above 82c, even on (heavy) climb-out with the components only permitted to cool for 30 mins between flights.
I know about the newer boxes having a small oil reservoir above each of the 90-degree input drives, but do they have a revised oil cooler system too?

Ambient temps here (UAE) range from 35 to 45c during the summer, with high RH and the atmospheric pressure as low as 993Mb during July and August.

Digressing: Once had a brand new (US-built) 139 that had it's initial compass swing during August and didn't make the second 8-point turn before both engines hit 140c, the IGB reached 110c and the #2 Hyd System was just above 120c (#1 Hyd hardly affected).
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Old 6th Jun 2017, 13:30
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Shouldn't make a difference where the hull is made. IGB's all made at Westland and the engines are all made at the same factory in Quebec.

The new MGB is the same internally as the old MGB with the same oil cooler and blower. Just has the two reservoirs added on top of the most critical element of the 139 MGB, the high speed inputs. Assures 30 minute run dry for O&G, even though the test MGB was run for a total of 1 hour without oil (you can pull it apart on the maintenance simulator in Italy if you are interested and check out the gears ).

If you're having MGB temp issues, pull the oil cooler and clean out the fins. If your mechanics are over greasing the swashplate (which a lot of Bell mechanics do!!!) then the excess grease gets flung off, clogging the fins on the cooler. You can see a 20C drop if it is very dirty.

As for a nominal MGB temp, anywhere in the green range Are you running air con. Are you running an AGB. are you running AC Generators. Are you running Super Silent gears. They all impart a load on the MGB, which will affect temp. Ambient temp also will affect MGB temp. I can tell you that the MGB runs nice and cool when it is -40C.

But the biggest factor I've found is a dirty/contaminated oil cooler.
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Old 19th Jun 2017, 11:58
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The preliminary report on this ditching has been issued (fairly promptly) - read it here

Preliminary Report

Assume the MGB cooling fan used here (manufactured by Technofan) would be the same in all AW139s? Looks like the fan had detached and one of the bearings had completely degraded after the cooling system had packed in
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Old 19th Jun 2017, 12:41
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While the fan is worrying, the bits that concern me about this report are:

  • Float punctured due to shear bolts not functioning
  • Liferaft failed to deploy
  • Cockpit window panel cracked, and
  • CPI failed to activate or deploy (again!)

I hereby motion to removal all CPIs for all aircraft, pile them into a ceremonial bonfire and dance around it!
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Old 20th Jun 2017, 09:23
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Qualification

Now the dust has settled a little on this incident ... could I remind the crew that they have now qualified to join a most exclusive club and we would like to welcome them to the shoal.

If you know the crew (or indeed any other unfortunate souls to have gone through this experience) please ask them to contact us.

This year we celebrate our 75th Anniversary and the reunion promises to be quite special.

Thanks and fly safely.

The Goldfish Club
(Facebook)
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Old 21st Jun 2017, 07:55
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I'm a little puzzled why they didn't return to the Dhabi II they'd just departed from? The initial warning came one minute into their climb, and even with a bit of time elapsing thereafter as things developed, I'm sure it would have been closer than the island they chose to route to 16nm away.
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