Marine Corps CH-53 Sea Stallion training at Fort Huachuca

FORT HUACHUCA — Fort Huachuca supports the Marine Aviation Weapons and Tactics Squadron One's training exercise here 6:30-8:30 p.m., Oct. 6. The exercise is conducted annually in April and October as the final training event for CH-53 Sea Stallion helicopters based in Yuma.

During the exercise, CH-53s fly into Libby Army Airfield and Hubbard Landing Zone. Marines exit the helicopters, secure selected areas and return to their aircraft. On LAAF, the group conducts a Forward Air Refueling Point event, refueling a couple of the helicopters from a KC-130. This is done while the aircraft's engines are on. Additionally, several C-130s and F/A-18s will provide overhead support.

The exercise ends with all helicopters and the KC-130 departing LAAF within the two-hour window.

Efforts are made to reduce the noise footprint of the helicopters crossing Huachuca City to the East Range, however residents in this area will hear the CH-53s flying in formation to and from the East Range.

While the exercise is being conducted, LAAF will close the airfield. A Notice to Airmen will be published to alert all local pilots and others intending to fly in during this time period. This provides a safe training environment and protects General Aviation from a military exercise.

Hello rlmorel, I've started hearing back from friends and colleagues. Here's one reply:

"The answers to many of your operational questions can be found in the "Seaplane, Skiplane, and Float/Ski Equipped Helicopter Operations Handbook" available for free download at www.faa.gov.

There are helicopters that are capable of performing continued operations on water (e.g. some CH-47 helicopters). There are some helicopters that are equipped with what are often called utility floats that allow routine operations to and from water. Some helicopters are equipped with emergency floats that are intended to allow the helicopter to remain afloat for emergency egress and possible helicopter recovery following an overwater emergency.

Corrosion is always a big concern when landing in water. Operations on or near salt water require anti-corrosion protection, inspection, and maintenance for continued airworthiness."

The FAA handbook is a good general source. The relevant chapters are here.

More soon!

Another reply, from the UK:

"I was Assistant Project Engineer. on the British Helicopters Civil Chinook program. One of the requirements was to be stable floating in sea state ? (can’t remember). We had one of our very capable engineers build a dynamically similar large model which we tested successfully in the Isle of Wight flotation tank. Can’t remember who owned it at the time but I think the history might have been Saunders Roe, Hovercraft, GKN and maybe now University of Southampton. Although the U Southampton tank may be new and the old Isle of Wight abandoned.

Anyway we passed the test. Our Chief Engineer, the late (and great) Chuck Ellis dragged me to London to brief the result to an Exxon? Chief Executive.

BAH’s four Chinooks did well initially: "Since its introduction by BAH in July 1981, the carrier’s Model 234LRs have transported a total of 604,000 passengers over 4 million revenue miles". But the downside of the story was the fatal accident caused by a transmission failure killed 47 people. Shell Oil immediately cancelled the contract for Chinook support. The cause of the failure is another interesting story for another time."

I wish he remembered what sea state the test was geared to! But at any rate, it's an indication that at least some models of Chinook were designed to be stable, afloat, at sea. At least for a while!

Here's an interesting thread from the Professional Pilots' Rumors Network. The "Boscombe" they are talking about is Boscombe Down, a big flight testing facility for the UK MoD. They have a test pilot school there, too. This seems to match what the Chinook engineer said.

A funny: http://militaryhumor.net/appearances/#

And, some very thorough and comprehensive insights from a retired USCG pilot:

"From 1970 to 1976 most of my life evolved around Sikorsky HH-52As in the USCG doing SAR in southeast Alaska and southern California....about 1500 hours crew and left seat, and lots of maintenance.

https://en.wikipedia.org/wiki/Sikorsky_HH-52_Seaguard

They stay upright on the water very well, especially when the head is powered because we have full control - a little collective can help. When the head is not powered they can stay upright provided the water is calm. Had experience with that. In the event of engine failure (or someone totally blowing an autorotation to the water), auxiliary flotation in the sponsons provide additional stability, however given enough sea state, they will turn turtle - typically about 16 degrees = tip over.

They float because the hull is fairly water tight. There's few penetrations on the wet side (bottom), and the penetrations on the dry side - such as cockpit controls - are "booted" to minimize foreign object intrusions. The cockpit/cabin deck (floor) sealed the dry side. The 52 hull usually had good water integrity,...and was known to float for days - usually upside down. It's bigger and younger sibling - the H-3, in all it variants - generally didn't float too long after unintentional water contact.

We usually put at least one of our helos the sea every day - so very aggressive and well practiced corrosion control practices are necessary. Generally included fresh water wash and engine wash after the last scheduled flight of the day. In our case (unscheduled SAR flights), that often meant full washes after every flight. Hulls were drained and flushed frequently, and scheduled inspections included lots of corrosion control practices. When ship board deployed, either on coastal ships or ice breakers at North or South poles, we had limited fresh water, so engine washes were done but the rest of the bird got only hand-brush washing.

Landings and takeoffs on water are similar, but not the same as on land. Landing on the water surface could be challenging, because we're not accustomed to the land "moving" under us, like water can. At night in glass-smooth very clear water, landing could also be tricky because our depth perception was challenged . Lift off from water took more power than land, all other things being equal, and there's no running take offs in water. Yes, tail rotor "ground" clearance is reduced on the water, so that was always on our minds on the surface (keep an eye on the waves). At the time, we believed 3 foot sea state to be max tolerable - but had to keep the bow to the sea..

The US Coast Guard used amphibs for many years because at the time it was the best way of rescuing people - directly from the water. When survivors were unable to climb into a rescue basket lowered from the helo, the helo could land and water taxi to the people to help them in the helo. As mentioned above, water landings were limited by the sea state, and consequently we lost people because we could not assist them. That lesson wasn't lost on the Coast Guard, which fully implement the "Swimmer Program", which we see today.

I don't know of any regular boat-hull operators today. Their advantage of water landing has been eclipsed by more powerful and capable machines which can easily accommodate the additional crew weight for a swimmer. In my time - except for night ops which required 2 sets of eyes on the front and one out back, many of our ops saw only 2 of us in the helo - the Aircraft Commander (PiC) in the right seat, and then the left seat crew. We'd fly to the scene, then the left seater would go out back to hoist or pick up people. "

So it would seem that while some helicopters were designed to be amphibious and it was intended to land them on water, those are older designs and not much used anymore. More powerful, modern helicopters have obviated the need for landing on water. But, in special circumstances (like the CH-47 video), they can still do it.

I hope this helps satisfy your curiosity a little bit, rlmorel! I like helicopters a lot, but the people who operate them, and design them, and figure out what to do with them -- that's what really interests me. I am always happy to learn more, and I am happy to share, so if you ever want to know anything else about helicopters, let me know and I will put the word out!

You are welcome, rlmorel, it was my pleasure. RE marinized aircraft or salt-water maintenance, I thought the exact same thing. The Coast Guard pilot said:

"We usually put at least one of our helos in the sea every day - so very aggressive and well practiced corrosion control practices are necessary. Generally included fresh water wash and engine wash after the last scheduled flight of the day. In our case (unscheduled SAR flights), that often meant full washes after every flight. Hulls were drained and flushed frequently, and scheduled inspections included lots of corrosion control practices. When ship board deployed, either on coastal ships or ice breakers at North or South poles, we had limited fresh water, so engine washes were done but the rest of the bird got only hand-brush washing."

I learned a lot too! So again, FRiend, it was my pleasure. I hope you have a great weekend!

Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.