Number crunching

Ever since the first floatplane ventured into the Canadian north, pilots have been using them to transport anything and everything. De Havilland Canada DHC-2 Beavers and DHC-3 Otters, and a variety of other aircraft on floats, have long been recognized as the workhorses of the north. Along with food supplies, clothing, and people inside their cabins, perhaps the most useful aspect of these floatplanes is their ability to carry an external load. 

Maybe a scientist needs to bring his canoe along with him; or perhaps some isolated residents are waiting for a load of lumber. Need a septic tank transported, or how about a moose head or even an ATV? Back in the day, many floatplane operators would just strap it on and go. 

Mike Toews, a Winnipeg, Man.-based expert in aircraft design and certification, has heard all kinds of stories about unusual external floatplane loads, but he admits he’s not keen to flight test some of them. “I’ve heard of some crazy loads flown in past: ATVs, jet skis, ladders, bicycles, sheets of plywood, beds, boat engines – just about anything you can imagine.”

Toews, who is a Transport Canada design approval representative (DAR) working for Perimeter Aviation, is the go-to guy when it comes to approving external load STCs (supplementary type certificates) for Canadian floatplane operators. 

“There may be another guy in Quebec doing these approvals,” Toews told Canadian Skies. “But I know for a fact that when a customer goes to Transport Canada (TC) and says they need external load approval, TC sends them to me.”

About six years ago, Toews fell into this role by chance, when an operator asked if he could do an external load approval. “I had no idea, so I called TC. My background is structures, not flight testing. I made a call, and happened to get the right guy. He sent me a sample data package and I had to customize it for my customer.” 

The rest is history, as they say. Since then, Toews has processed more than 50 external load approvals for floatplane operators across Canada. He’s been as far north as Norman Wells, NWT, and has visited operators in Yellowknife, Whitehorse, and various towns in Northwestern Ontario. 

So, what’s changed since the days of the “load it and go” mentality? For one thing, Transport Canada is paying closer attention to what floatplanes are carrying these days. 

“Operators have been flying these planes for 50 years with external loads, and for the most part all has gone well,” said Toews. “But TC has certainly been watching where the risks are. There are a number of older planes where external loads are already part of the type certificate for the airplane. But, in many cases, that approval came with the original old radial engine, or there have been equipment modifications over the years. So TC says, hang on, these airplanes have changed. It’s a different airplane now.”

That’s where Toews can help. When an operator contacts him to inquire about an approval to fly a specific external load, he first consults his database to make sure he hasn’t done the same approval in the past – on the same aircraft, with the very same equipment, and with the same proposed load. “If so, I give them a price to re-sell that approval to them – I have the data, but the original operator who provided the airplane owns the data, so I go back to them and make sure it’s OK to sell it, and then I give them a cut.”

If Toews hasn’t already done the approval, he prepares a compliance plan to outline what regulations need to be met. Then, a test plan is prepared for TC approval. Once that is obtained, Toews schedules a visit to the operator for flight testing.  

“Testing can take anywhere from two days to a week,” he explained. “We do all sorts of calibrations of the airplane: we make sure the airspeed and altimeter are calibrated; and that the manifold pressure gauge for piston engines and the torque indicating system for turbine aircraft are calibrated. This ensures we’re going to get good data. Then, we do baseline flights without any external loads. We’re checking to make sure the airplane’s performance is what the OEM says it should be. We’re often dealing with older aircraft, and over the years they may have acquired different equipment, so we need a baseline measurement.”

With the external load installed, flight testing begins at lower weights and gradually increases to gross weight. “We take it in small increments, and we’re always reconfiguring the airplane. We spend lots of time moving ballast around,” said Toews.

In total, he added, it takes about eight hours of flight testing to approve each separate type of external load. After the flying is complete, Toews returns to his desk to settle into about two weeks of data reduction. “I don’t mind that part. Certainly, being on the water and flying is the most enjoyable. But I like coming back and reducing the data and finding solutions for the customer. If the numbers don’t work, the most common resolution is that we have is to start taking weight off the airplane – imposing weight limitations.”

Once the data has been crunched, Toews sends his final report to a flight test expert at TC in Ottawa, who reviews it before sending it off to the regional office in Winnipeg, where it is signed off. 

Operators can obtain a serialized STC – which covers certain specific registrations within their fleet – or a blanket STC that will cover all aircraft of that type and configuration in Canada. Most times, the less expensive serialized STC is all an operator needs, although it’s still not cheap. Toews said operators should budget a minimum of $6,000 to obtain an STC to carry an external load, which does not include TC fees, taxes, or the fuel required for flight testing. 

“It’s frustrating for them [floatplane operators],” he said. “They’ve been carrying these loads for years but now they must be approved. If there was ever an accident and they had not obtained the approval, their insurance would not cover them. So what we’re aiming for is a safe, repeatable way of approving these external loads. We’re putting things in place to mitigate the risk that we’re seeing.”