Date: 201508
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Aircraft: Dash 8-300
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Parked
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown; Time Pressure; Situational Awareness
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown
Detector: Person Flight Crew
When detected: Aircraft In Service At Gate
Result: Flight Crew Became Reoriented; Flight Crew Took Evasive Action
Contributing factors: Weather; Human Factors; Staffing; Aircraft
Primary problem: Human Factors

Narrative: At 5 minutes to departure; the ground crew signaled to disconnect the GPU. I signaled that we needed to start engine #2 first. The ramp agent cleared our #2 engine and then returned to the left side of the aircraft nose. As I introduced fuel to the #2 engine; I saw a lavatory service cart pull up to the lavatory port just ahead of the #2 engine. I aborted the start by cutting fuel and disengaging the starter. The lavatory cart stopped at the port and quickly reversed away from the aircraft as the driver realized our engine was starting. The FO waved the cart away. The driver paused near the gate off our right wing tip. I did not turn off the red beacon. I timed a minute on my clock and then dry motored the starter to clear fuel from the engine. The lavatory cart came back! Again the driver looked left and saw the prop begin to turn as the engine spun without fuel. The cart driver gave us a very frustrated scowl and backed away again quickly. This time the cart left the area. I decided that we would wait until pushback to start the engine. We turned off the air conditioning packs and disconnected the GPU to wait for push back.We had called in-range during the previous flight requesting lavatory service. The aircraft was on the gate between flights for 50 minutes. This aircraft was a 300 series model. In the summer it is standard practice to use a Ground Power Unit; GPU to supplement the APU when running both air conditioning packs. Because of this poor reliability of the APU in the summer; my preference is to start an engine before disconnecting the GPU.The lavatory was not serviced during the first 45 minutes of the 50 minute sit. I did not expect the lavatory cart to arrive 5 minutes to departure time. Lavatory service frequently never comes and is not always worth delaying a flight.Although we were operating the red tail beacon prior to start; the lavatory service agent only realized that the engine was starting when the lavatory agent saw the prop turning. The ramp agent who had cleared our engine start had returned to the left side of the nose; ready to disconnect the GPU; and was not in a position to waive off the lavatory cart.Firstly; we would all benefit from more reliable APUs. I assumed that the lavatory would not be serviced 5 minutes before departure and that the lavatory agent would not make a second attempt after seeing the propeller begin to spin. Although we have no direct communication with the lavatory agents; I could have called station operations to cancel the lavatory request.We have procedures to safely start engines at the gate; a ramp agent to visually clear the area and a red beacon to signify engine operation.Ramp personnel that clear an engine start should watch the engine area when it is running. The flight crew cannot see personnel approaching from the rear of the aircraft.The red beacon on the Dash-8 is not very effective in daylight hours because it is a single lamp located 25 feet above the ramp surface. Newer aircraft incorporate belly beacons that are more likely in the visual field of service personnel approaching the aircraft. Training for ramp personnel should include emphasis on this difference of the Dash from other aircraft types. Our spinning propellers are large visual cues to engine operation but provide no advanced notice.Lastly; if our service personnel are not able to make scheduled and requested visits to the aircraft; there are probably not enough agents or equipment. The pattern seems to be that on request; but foreseeable services such as wheelchairs; passenger loading devices; window washes; and lavatory service frequently do not come as requested or arrive after much delay. In the case of lavatory service this can be a safety risk. Station managers should schedule adequate equipment and personnel.




Synopsis: While starting engine 2 at the gate; a DHC8-300 Captain detects a lavatory service truck approaching the service port just ahead of the engine and terminates the start. Motoring of the number 2 engine is attempted to clear unburned fuel and again the lavatory service truck approaches the aircraft before detecting propeller movement and backs away for good.