Professional Pilot, July 2020

20 PROFESSIONAL PILOT July 2020 At or above FL400 Autopilot and autothrottle engaged Red cabin pressure low message displayed Autothrottles retard to idle Guidance panel initiates Altitude change to 15000 ft Course change to 90 left turn Airspeed change to VMO MMO Don 02 masks Deploy passenger 02 masks Contact ATC when possible Once 15000 ft is established Autothrottles advance to command 250 kts Extend speed brakes Does ADM work A few years ago ADM was installed on my companys aircraft The owner asked How do we know it works as described So we set out to satisfy the owners question We read the literature and trained with ADM in the simulator In the sim ADM worked as advertised of course How to functionally check the system How do owners know that they are getting what they paid for We created a functional test plan that would be conducted off Floridas gulf coast on an empty leg The plan was to depressurize the cabin by depressing the DUMP push button but Falcon 2000LX only allows dump to cabin altitude of 14500 ft To raise the cabin further to the 15000 ft trigger threshold we would need to shut off all incoming pressurization air We would follow the Falcon maintenance procedure for the inflight check of cabin sealing which instructs the operator to turn off all incoming air and then monitor cabin altitude We planned to turn off the cabin oxygen system to prevent passenger oxygen mask deployment and have the pilots wear oxygen masks to eliminate the risk of hypoxia Airspace coordination was a challenge because there was no way to instantly trigger ADM to function and because of the rapid descent and 90 degree turn We worked with Miami Center for a southbound track through Gulf of Mexico Warning Areas that were not in active use by the military We coordinated a clearance to descend and turn at pilots discretion since there is no clearance for descend at airplanes discretion Observations The cabin leak rate on the Falcon was amazingly slow With all flow into the cabin turned off the cabin altitude took over 2 minutes to rise from 14500 ft to the trigger altitude of 15000 ft When ADM activated the pilots saw amber flashing ADM indications in both the vertical and horizontal flight mode annunciator windows as expected ADM is much more benign than the emergency descent practiced in the simulator for 2 reasons First the airbrakes do not deploy automatically thus the descent rate is similar to an everyday descent Second the turn is done gracefully at half bank ADM worked as expected giving the owner confidence in the newly installed software Even with ADM protection the first step in any depressurization event is to put on the oxygen mask Closing Prior to ADM installation we would routinely hand fly the aircraft to cruise altitude to maintain hand flying proficiency With ADM protection only available when AP is engaged we changed our standard operating procedure to engage AP by 30000 ft to gain full ADM protection Gulfstreams Heidi Fedak reports that Gulfstream is aware of 2 AEDM activations in its 22 years of operational service Do you have knowledge of any saves If so consider reporting the event to your aircraft manufacturer NASA or FAA If your oxygen system was inadvertently filled with pressurized air how would you know until it was too late Normal preflight tests only check for flow of gas not gas chemistry A simple and inexpensive pulse oximeter device could help While breathing normal cockpit air at cruise altitude the pilot can self administer a pulse oximeter reading and then breathe 100 oxygen through the oxygen mask for 60 90 seconds before taking a second pulse oximeter reading Breathing 100 oxygen the pilot will see a noticeable increase in pulse oximeter reading likely to 100 blood oxygen saturation Summary illustration of ADM activation requirements and expected sequence of events in Gulfstream aircraft Marty Rollinger has over 35 years of flight experience in 68 different aircraft A career US Marine Corps pilot he was a Liethen Tittle Award graduate of USAF Test Pilot School He is director of flight ops for a Midwestern operator and a member of the Falcon Operator Advisory Board