IATA’s Maintenance Cost Task Force has found that for 20 major airlines that have reported consistently over the years, average narrowbody maintenance cost per aircraft reached $2.57 million in 2015, up from $2.27 million the year before. MRO cost per flight hour were also up, to $854 in 2015, compared with $743 in the year prior. The trend was the same when measured in cost per flight cycle, $1,490 in 2015, versus $1,285 in 2014.
Part of the explanation is age. The reporting carriers had narrowbodies with an average age of 8.1 years in 2015, versus 7.7 years in 2014.
Interestingly, widebody maintenance cost dipped slightly in 2015 for these 20 carriers, to $6.18 million after $6.24 million in 2014. Per-hour and per-cycle costs were also down.
For all 47 airlines reporting in 2015, large widebody maintenance cost $7.3 million per aircraft, $1,762 per flight hour and $11,703 per flight cycle. The same figures for regional jets were $2.0 million, $831 and $1,173. For turboprops, MRO in 2015 cost $1.7 million, $844 per hour and $765 per cycle.
Everyone in aviation remembers that an ice-clogged air-speed sensor, or pitot tube, was one link in the causal chain that brought Air France flight 447 down. Redundant pitot tubes and other systems and procedures should prevent such a single failure from having fatal consequences. Still, it would be nice if the chances of any pitot tube failure could be minimized.
Carl Hensley, Air Data Sensors Product Line Manager at UTC Aerospace Systems, says UTAS has developed a new pitot tube that is far better protected against icing dangers. It has started to be installed on new aircraft and Hensley hopes operators will consider it as an easy and wise retrofit on existing aircraft.
Commercial aircraft usually have three or more pitot tubes, and systems are designed to ignore a single air speed that is out of line with other speeds reported. Each tube now has a heater and drain system to minimize icing possibilities. “But in the last several years we have better understood icing conditions,” Hensley says. “We tried to develop new probes that perform in severe ice.”
Fewer or no failures would at least mean better reliability, less maintenance cost and perhaps major operational savings. Hensley says some carriers turn aircraft back when a pitot tube fails, even with backups working.
The improved UTAS pitot tubes are now on two new commercial aircraft models in revenue service. The devices are not required for new aircraft yet, but Hensley expects they will be when a new FAA Technical Standard Order is finalized in 2017.
He is then looking for retro-fit opportunities. The new tubes are drop-in replacements that require no changes in wiring, software or mounting. Replacing the old tubes should usually take about an hour.
Hensley does not think there is any other device that will meet the tough new standards that are coming, at least for new aircraft. One reason is that UTAS has a very advanced wind tunnel for testing icing dangers in its Minnesota facilities. The tunnel can simulate any condition in the flight envelop of a commercial jet that might generate ice crystals in the pitot tube.
That has enables UTAS to design and validate a unique pitot tube, for example by modifying the tube’s inlet to slow down ice accumulation and give the heater more time to melt ice, all while preserving the needed degree of accuracy in measuring air speed.