Huey Replacement Begins Testing

[MIflyer]

From Air Force Magazine:

The Air Force will receive its first MH-139 helicopter for testing in December, as it enters the next phase of the $2.4 billion effort to replace the Vietnam-era UH-1N Hueys, the head of Air Force Global Strike Command said Sept. 18.

Boeing and Leonardo are teaming up to provide the MH-139s, a new military variant of a civilian helicopter the Air Force chose one year ago. The fleet of up to 84 airframes will replace Bell-made UH-1 Hueys at nuclear missile fields across the US and for other transport and VIP missions. After years of trying to get a helicopter on contract, the Air Force required that Boeing deliver the first two aircraft by the end of 2019.

"We have a very good helicopter, and everything is on track," AFGSC Commander Gen. Tim Ray told reporters at
AFA's Air, Space & Cyber Conference. "I'm knocking on wood, but I'm very pleased to see that we're getting ready to have the first aircraft for test delivered here in December."
He added that airmen expect to receive operational helicopters in fiscal 2021. In fall 2018, the Air Force said it planned to accept ready helos through fiscal 2027.

 

[DerAdlerIstGelandet]

I love the Huey, always have, always will...

The MH-139 is an awesome helicopter though. The company I used to work for, is the largest civilian operator of it in the world (AW-139). We used it for passenger transport, cargo, and SAR. Very reliable, and a good performer.

 

[Tieleader]

Still has a lot of the classic Huey lines on it

 

[DerAdlerIstGelandet]

Still has a lot of the classic Huey lines on it

Not really. At least not when you put them side by side. We still operated a few Hueys as well.

 

[Sid327]

The AW139,

when it first came out, it was called the AB139 (Augusta Bell). The company I worked with ordered twenty of the early production batch.
It certainly went through more than a few problems.
They initially were built with a titanium exhaust system, which had a habit of cracking and collapsing, this was changed to a stainless steel system which gave a 39Kg weight penalty aft of the C og G.
The tailbooms started giving problems too, they weren't made strong enough to take the yaw stresses. A stronger one with reinforced stringers and alloy rather than the initial composite honeycomb sandwich was used. This was 14Kg heavier, again well aft of the C of G. (One of our 139's went through three tailbooms before it had 500hrs TT on the airframe).

Subsequently AW moved the MAU's and some electronics from just rear of the mast into the nose and extended the nose cone to help with restoring the C of G problem. Though they still hovered almost ten degrees nose-up.
There were many other problems, but it's pretty much okay now and they are better suited to a more temperate climate.

Whoever designed the MR-Head deserves a medal though, we received the brand new aircraft in large crates and assembled them ourselves. Taking the MR blades out of the delivery boxes and when checking initial vibration levels, they were incredibly low. No adjustements were necessary, they were showing readings of 0.07 IPS and lower. We even removed an in service blade from one and fitted it to another and when checked it didn't need any adjustment whatsoever.

As a comparison, the Bell 212s and 412's were were operating, we were lucky to get (particularly) the 412's below 0.3 IPS and they would not stay there for long before an elostomeric bearing or damper gave trouble and it went out of track or balance, or both. Whereas the 139's would remain good and wonderfully smooth right up to VNE.

Attachment: 1] The company's first AW139 in June 2016.
2] Gulf Helis tail boom 2009.

 

[DerAdlerIstGelandet]

The AW139,

when it first came out, it was called the AB139 (Augusta Bell). The company I worked with ordered twenty of the early production batch.
It certainly went through more than a few problems.
They initially were built with a titanium exhaust system, which had a habit of cracking and collapsing, this was changed to a stainless steel system which gave a 39Kg weight penalty aft of the C og G.
The tailbooms started giving problems too, they weren't made strong enough to take the yaw stresses. A stronger one with reinforced stringers and alloy rahter than composite honeycombe sandwich was used. This was 14Kg heavier, again well aft of the C of G. (One of our 139's went through three tailbooms before it had 500hrs TT on the airframe).

Subsequently AW moved the MAU's and some electronics from just rear of the mast into the nose and extended the nose cone to help with restoring the C of G problem. Though they still hovered almost ten degrees nose-up.
There were many other problems, but it's pretty much okay now and they are better suited to a more temperate climate.

Whoever designed the MR-Head deserves a medal though, we received the brand new aircraft in large crates and assembled them ourselves. Taking the MR blades out of the delivery boxes and when checking initial vibration levels, they were incredibly low. No adjustements were necessary, they were showing readings of 0.07 IPS and lower. We even removed an in service blade from one and fitted it to another and when checked it didn't need any adjustment whatsoever.

As a comparison, the Bell 212s and 412's were were operating, we were lucky to get (particularly) the 412's below 0.3 IPS and they would not stay there for long before an elostomeric bearing or damper gave trouble and it went out of track or balance, or both. Whereas the 139's would remain good and wonderfully smooth right up to VNE.

Attachment: 1] The company's first AW139 in June 2016.
2] Gulf Helis tail boom 2009.

All or those problems seem ti have been fixed. The tailbooms have been strengthened and the other kinks have been worked out.

 

[Sid327]

All or those problems seem ti have been fixed. The tail booms have been strengthened and the other kinks have been worked out.

Other ''kinks'' included throwing tail rotor blades, that caused a complete grounding of all 139's for a time because of the fatal crashes. The first occurring with a Brazilian company in about 2010. Then the fan drive problems (a small drive shaft from the MGB to drive the cooling fan for the rather small MGB oil cooler) which caused the MGB to overheat and the 139 ditched as a consequence. That was in 2017.
The MGB itself is also a very good piece of kit, just the oil cooler assembly is a bit weak and the MGB can tend to run higher than the nominal temp of 82c.

It has plenty of power from the PT6-67Cs:
The 139's were first limited to 6400kg MAUW and were fully compliant with most Cat 'A' procedures to Perf Class 1 apart from initial take off to Vy, depending on conditions (OAT & DA). It then got approval for 6800kg with obvious restrictions to most Cat 'A' procedures and subsequently they were approved to 7000kg with even more restrictions.
This was done to try and compete with the Helibus H175 which came out of the factory at 7000kg and is now at 7800. Which is frankly a better engineered and built medium. When comparing the build quality and standard of fit and finish between the 139 and the 175 there is a stark difference. It's like comparing a Fiat with a BMW.

The engine (PT6-67E) installation on the 175 is also way better with both engines having a short exhaust ejecting out of the side and the intakes (which are behind the exhaust on the PT6 series) have been built onto the forward upper cowling to take advantage of ram air. Whereas the 139 engines have the exhaust coming out of the inboard side of the engine then turning through almost 270 degrees to route between the engine and the firewall to finally exit at the tail of the rear cowling. This causes massive heat build up in the engine ''compartment'' and the engines then run at an abnormally high oil temp (there are no oil coolers for the engines). They actually over temp in the desert summers during the two minute ''cool down.''
The other consequence is they de-laminate the engine deck, because of this exhaust design. Every 139 in the previous company had this problem; AW accepted ''our'' fix and applied it to all 139s as the approved repair.
They (AW) also developed a larger rear cowling with more air ducts to try and alleviate this problem.

So yes, most of the problems have been engineered out of them and at the end of the day, they are a great thing to fly as long as you are careful of the tail when doing a hover landing.

Attachments: 1] Early production short nose 139 with titanium exhausts and initial rear cowling.
2] Modified factory short nose with the strengthened tail boom, larger rear cowling and plug type cabin doors.

 

[DerAdlerIstGelandet]

Yeah, I had to do a nice offshore accident analysis going back to 1950, that included every accident/incident. Was pretty interesting to see how the policies and procedures where typically written in blood.

 

[MIflyer]

I have to wonder why they did not use the US Army's new UH-72. Mission sure sounds similar. Photo from Wikipedia.

 

[Sid327]

I have to wonder why they did not use the US Army's new UH-72. Mission sure sounds similar. Photo from Wikipedia.

View attachment 554381

This helicopter is too small (and underpowered) to be a viable UH1H replacement.
They have a max take off weight of around 3,500kg an old Bell 212 (twin Huey, MAUW 5,080kg) could lift a better payload and be about ten times more reliable, as well as carry thirteen troops not just nine (albeit at a slower cruise speed) and in higher Temps and DA conditions, particularly when fitted with the ''high power'' kit.

The commercial version of these (so lower basic operating weight) had problems lifting half the designed payload in hot and high conditions. They also had problems with the gizmos failing in the desert heat.

It was often said, you could bury a B212 in the desert or in the snow half-way up a mountain and just remove the battery. Leave it there for six months, dig it out, fit the battery and it would fire up and work. Try that with any modern type. You can start to understand why the ''Huey'' was so well loved. You could get inside the cockpit and swing a sledgehammer around, jump on everything with hob nailed boots and it would still crank into life.

 

[DerAdlerIstGelandet]

I have to wonder why they did not use the US Army's new UH-72. Mission sure sounds similar. Photo from Wikipedia.

View attachment 554381

The Lakota does not have the capability. It cannot carry the passengers or cargo per the requirement.