Gulfstream Aerospace expects to issue a software fix later this year for its G500 fly-by-wire flight controls following a hard landing event of one of the large-cabin business jets in gusty winds. The OEM issued a new maintenance and operations letter last week that reiterates previous guidance in the airplane flight manual (AFM) with respect to control inputs and approach speeds when landing in gusty conditions. Further, it plans to release an AFM revision to provide updated operational procedures, limitations, and warning notes.
Meanwhile, Gulfstream expects an applicable FAA alternate means of compliance (AMOC) to an existing and related 2020 airworthiness directive (AD 2020-05-12) to follow shortly. Gulfstream said preliminary aircraft data analysis suggests that the hard landing occurred after the aircraft flight control system entered Angle of Attack (AOA) limiting mode at approximately 12 feet agl following a series of large, rapidly alternating pitch stick inputs.
The new limitations in the AFM include maximum landing wind speed of 15 knots, including gusts; maximum gust speed of five knots; approach speed additives (flaps 39) are half the steady state wind plus the gust increment up to a maximum additive of 20 knots; all approaches stabilized by 1,000 feet altitude before landing; mandatory vertical guidance required from ILS or FMS-based approaches before night landing; minimum approach speed is Vref+10 to the threshold and used to calculate landing distance and autothrottles required during normal approach, landing, and operations with pilots to physically guard and override in the event of performance anomaly.