German airline Lufthansa (LH/DLH) is responding to a recent EASA airworthiness directive (AD) for the Airbus A320neo as the manufacturer has concerns about the aircraft’s center-of-gravity (CG) limitations. The problem is similar to the one detected in July 2019 for the larger Airbus A321neo aircraft. For this reason, Lufthansa decided to block the last row in the Airbus A320neo, with both aisle seats remaining available as possible crew seats. The airline informed their crews with a memo about the concerns.
The vulnerability was discovered during simulations and analyzations, but never in a real flight. Thus, with certain configurations of the aircraft, in combination with special maneuvers of the pilots, the protective measures of the aircraft may not work properly at too steep angles of attack. Aviation Week calls aggressive go-around maneuvers as an example.
The AD reads that “reduced efficiency of the A320neo Angle of Attack (AoA) protection under certain flight conditions, and in combination with specific command maneuvers from the flight crew, could lead to excessive pitch attitudes, possibly increasing cockpit workload conditions. This potentially unsafe condition, although never encountered during operations, was discovered during analysis and laboratory testing of the A320neo flight control laws.”
This means under certain conditions and maneuvers, the center of gravity of the aircraft could move too far back. During laboratory testing, it was detected that the aircraft’s aileron, elevator, and the related elevator and aileron computer (ELAC) software compensator showed a defect. But there have to be two things first to get into this dangerous situation. The Airbus A320neo must be set up in a landing configuration with a center of gravity near its limit in the aft part of the aircraft. Additionally, it then takes a sudden maneuver, such as an aborted landing, to cause the nose of the aircraft to straighten up more than would normally be the case in a go-around.
Due to this potential problem, Airbus has informed all Airbus A320neo operators of a temporary change in the location of the center of gravity. Lufthansa is one of the first airlines to react to these concerns and therefore is blocking the last row so that the center of gravity of the aircraft is not too far behind the center of the fuselage.
While the problem has yet to occur during flight operations, there are some reports of Airbus A320neo operators with a certain cabin layout called Space-Flex having common problems during the ground operation. For example, Lufthansa has to unload the luggage from the aft and bulk cargo compartment first when passengers are still on board as the aircraft could tumble on its tail in the worst case.
According to the memo, the airline is working on measures to use the last row again. Lufthansa, however, expects the new limits to remain in place until mid-2020 when Airbus will release a revised flight control software. However, these difficulties would not solve the problems for the ground operation.
In a statement, Airbus said they are working together with the Airbus A320neo operators to find the best solutions for their daily business.
The findings are in no way comparable to those of the Boeing 737 MAX, which led to the world-wide grounding of the MAX fleet. On the Airbus A320neo, the computer never overwrites the actions of the pilot flying the plane. This is in direct contrast to the Boeing 737 MAX and their MCAS, an anti-stall prevention system that prevents the pilot from intervening during an over-deployment situation.
As the EASA has not issued a critical directive, the Airbus A320neo can still be flown by the airlines, which can take steps to temporarily fix the problem until Airbus will issue a final solution.