E-Jets Verdict: Cargo door problem & Numerous upgrades

Cargo door problem

The cargo doors on LOT’s E-170s are the only ones in its fleet that “require very careful maintenance in order to be reasonably operational – it is unacceptable”, says Buczko. “We were fortunate that last winter the temperatures were not low enough to cause us problems, but we know from other operators like Air Canada and Finnair that the problem exists. This issue has lasted three winters and Embraer must solve it.”

Finnair’s assistant vice-president fleet management Maúnu Visuri says: “We’d heard about the cargo door problem from LOT and told Embraer about a year before entry into service with us that it has to be fixed, and they took it seriously. We had a few cases when we started, but we changed the grease, and it’s under control by applying better lubrication more often,” he says.
The E-Jet’s high level of complexity and sophistication also generated headaches early on for operators. “The E-170 is a flying PC, and it doesn’t like cockpit ninjas – pilots who are used to old-fashioned electro-mechanical systems make fast switchings and expect immediate responses,” says Buczko. “Procedures must be followed exactly, as the order in which things are done is very important.”

This resulted in many spurious warnings when the E-170 was introduced. To overcome this, LOT has progressively introduced some manufacturer-specified timings into procedures. “For example, make a selection and pause for 5s while the system waits for responses,” says Buczko. He adds that if other selections are made during this “wait period”, the system will be interrupted and can result in a false warning that it is inoperative. “A fault in the fly-by-wire system could be falsely indicated because it assumes during the built-in test that the controls would not be touched. You have to be patient.”

Buczko says that “just like a PC, you can restart [power-down and power-up] and allow the system to run through the checks again. Alternatively you could try to solve the ‘problem’ indicated, but usually the problem was non-existent. The aircraft was not always user-friendly and forgiving of mistakes.”

Numerous upgrades

The Honeywell avionics system, which can be updated in “a few hours” with software loads just like a PC, has been subjected to numerous upgrades, “but as with any new software, you fix some problems and introduce new ones”.

The majority of electronic boxes can also be upgraded during overnight stops by a technician with a laptop PC, says Buczko. “This can change the behaviour of a particular aircraft from day to day, depending on whether boxes have been reconfigured.”

This made LOT’s transition period to the E-170’s new technology “extremely difficult” for pilots and mechanics as it was hard to establish if faults had been fixed or if warnings were spurious. But as the airline has built experience on the aircraft these problems have reduced significantly.

The major problem LOT has suffered in the recent past has been build quality. “In 2006 there were problems in structural and electrical areas – for example some incorrect riveting and problems with wiring harnesses,”
says Buczko. He adds that Embraer was extremely responsive to these problems and that the build quality has improved noticeably with each batch of new aircraft. “We accepted six aircraft in 2004, four in 2005 and four in 2006, and from year to year there is a clear improvement in how the aircraft behaves.

“Last year’s batch has all the latest hardware upgrades and its dispatch reliability today is above 99%, whereas our older aircraft are at around 98.5%.” Buczko says that LOT’s entire E-Jet fleet dispatch reliability is now at around 98.7%, having been as low as 93% during the early months of operation in 2004.

“The E-Jet fleet is second to our 737 fleet, but given the maturity of that product I think that the Embraer is performing really well,” he says.

While early problems were more associated with software, there has been a shift now towards issues with hardware, says Buczko. He says that there are many modifications and retrofits being implemented on the older aircraft to bring their reliability up to the level of the newer aircraft, but this programme will take some time to complete. One problem area subject to a retrofit programme was the Parker hydraulic pumps which had been leaking, but Buczko says the response of the supplier was “very good…they quickly identified the problem and launched a retrofit”.

From a maintenance perspective, the aircraft is a “challenge” and needs to be fully understood before mechanics are comfortable working on it, says Buczko. “The aircraft is fly-by-wire, steer-by-wire and brake-by-wire, so everywhere you have electronic boxes and logics. The integration of the systems and subsystems means that you may be trying to resolve a problem with the air conditioning and the real problem is with the de-icing,” he says. “The central maintenance computer is a great tool, but you have to fully understand how to use it.”

Source: Flight International