Franco-Italian aircraft maker ATR and engine supplier Pratt & Whitney Canada (P&WC) have begun studies on higher-weight applications of the 48-seat ATR 42-500 and 68-seat ATR 72-500 turboprops.

ATR hopes to increase both models’ mtow by 660 pounds, to accommodate higher FAA assumptions for average passenger weight. According to marketing vice president Mario Formica, the ATR 42 will accept the higher mtow without structural modification. The larger ATR 72 will need reinforcements to the tailcone and wings.

The manufacturer hopes to win formal airworthiness approval for the change early next year. The move would increase the ATR 72’s mtow from about 49,600 pounds to 50,260 pounds and that of the ATR 42 from 41,005 pounds to around 41,660 pounds. Zero-fuel weight for the two aircraft will increase by the same margin, to about 37,500 and 45,860 pounds, respectively.

The FAA has moved to raise the assumed passenger and baggage weights that airlines use in calculating aircraft weight-and-balance for flight planning. The action follows investigation into the cause of last year’s fatal accident of an Air Midwest Beech 1900D in Charlotte, N.C.

Chief executive Filippo Bagnato said ATR has approached P&WC about raising the available maximum continuous power from the ATR 42’s 2,400-shp PW127E and the ATR 72’s 2,750-shp PW127F engines to still unspecified levels.

Although the company plans to introduce the performance mods along with avionics and cabin-interior improvements, the resulting airplanes would nonetheless not constitute new variants of the ATR family, according to Bagnato. The official said that ATR’s customer base now includes more operators flying from high-altitude airports and/or in hot temperatures that demand the extra power margin.