SINT MAARTEN – As one might intuitively guess, maintaining floatplanes and amphibians – particularly those which routinely operate commercial charters or scheduled services and need to provide very high levels of operational reliability – is a rather more specialized and MRO-intensive business than is maintaining aircraft which fly only from runways on land.
Interviewed by MRO Network at the Caribbean Aviation Meetup conference in Sint Maarten this week, John Kelly, CEO of East Haven, Connecticut-based Cessna Caravan floatplane operator Shoreline Aviation, says that for every water landing one of its seven aircraft makes, the company puts the Caravan floatplane through three hours of MRO.
Floatplanes and other seaplanes of necessity require more maintenance than do land-based aircraft for two reasons, says Kelly. One reason is that, every night, when one of Shoreline’s seaplanes returns from water-based operations to one of Shoreline Aviation’s two main bases – one is in East Haven and the other is at the Bohlke International Airways FBO in St. Croix in the US Virgin Islands – two employees must hose down the exterior surfaces of the aircraft with fresh water and give its PT6A-114A or PT6A-140 turboprop engine a thorough compressor wash. (Shoreline Aviation has four Caravan floatplanes with 675shp PT6A-114As installed and three fitted with 867shp PT6A-140s.) In total, these daily processes, required to prevent salt crystals from building up on the compressor blades and to prevent airframe corrosion, take from 45 minutes to an hour.
The second reason is that aircraft which land on bodies of water – particularly salt water – require much more preventive maintenance in general than do land-based aircraft, according to Kelly. This is partly because they must be extremely reliable when operating to and from remote beach locations. “The aircraft is taking off from and landing in locations where you have no support and where it is difficult to get support to,” he says.
If a floatplane becomes unserviceable at a remote beach on a remote, uninhabited island in the Bahamas or the Caribbean – the type of destination served frequently by Shoreline Aviation and Tropic Ocean Airways, a Fort Lauderdale-based Caravan EX floatplane operator which brought an aircraft to the Meetup for demonstration flights – then it could be out of service for several days. This potentially disastrous situation makes it imperative for floatplane operators such as Shoreline and Tropic Ocean to adopt extremely conservative practices with regard to their inspection intervals and replacement of life-limited parts.
The other reason floatplanes require a lot of preventive maintenance is that “a seaplane landing on water has no shock absorption”, says Kelly, who established Shoreline Aviation in 1980 and pioneered the thriving summer-months floatplane market between the busy East 23rd Street Seaplane Base in Manhattan and the posh Hamptons and Montauk resort destinations on the south shore of Long Island. Floatplanes always experience considerable stresses on their floats and airframes when landing on water and “this works the rivets and bolts”.
Consequently, Shoreline Aviation – which has its own FAA-approved Aircraft Inspection Program (AIP) – does “far more than the manufacturers require” in terms of performing required and preventive maintenance. To ensure operational reliability from remote locations, for instance, Shoreline changes each aircraft’s three-year-life-rated battery after just a year. It also changes out starter generators, rated for 2,500 hours of operation, after 700 hours.
Not only does Shoreline work with the aircraft OEM and the suppliers of components to the Caravan floatplane to make sure that all inspection intervals are suitable, but it also does more under its own AIP. Shoreline removes the rudder, fin and elevator assembly from each of its aircraft annually to inspect for corrosion in areas of the aircraft which normally can’t be inspected visually.
It removes each aircraft’s floats – which are multi-flotation compartment, aluminum Wipline 8750 floats made by Wipaire – every two years “and we inspect every trunnion, bolt and rivet”, says Kelly, ensuring that each is tightened optimally. Another important task for Shoreline’s maintenance department is to make sure it applies all the required anti-corrosion greases and coatings to each aircraft at least as often as is required by its AIP.
Shoreline’s operation is seasonal: its New York-Hamptons operation peaks from mid-May to mid-September and its Caribbean operation peaks between November and April. “With seasonal operations, we have to use the downtime to do maintenance,” says Kelly. “Every one of our aircraft spends three weeks to a month in the hangar every year, longer if necessary. Anything that is going to fail in the next 200 to 400 hours, we deal with,” during the annual hangar visit.
These very stringent maintenance practices ensure that Shoreline Aviation maintains an enviable level of dispatch reliability. “In the summer, our dispatch reliability is 99 percent – we almost never cancel a flight” for technical reasons, says Kelly. “If we have any maintenance issue, the aircraft is usually only down for an hour or two.”