History of Flight
On July 23, 2015, about 2045 eastern daylight time, an Israel Aircraft Industries 1125 Westwind Astra, N765A, returned to land at Baltimore-Washington International Thurgood Marshall Airport (BWI), Baltimore, Maryland, after the main entry door (MED) opened in flight. Both airline transport pilots and the five passengers were not injured. The airplane was registered to GMH Capital, LLC, and operated under 14 CFR Part 91 as a business flight. Visual meteorological conditions prevailed and an instrument flight rules flight plan was filed for the flight destined for Chicago Executive Airport (PWK), Illinois. The flight was originating at the time of the accident.
According to the pilot monitoring (PM), after passengers boarded, he closed, locked, and visually checked the MED handle pin. During starting, the red CABIN DOOR annunciator light remained off. Throughout engine start, taxi, and takeoff, the red CABIN DOOR, amber CABIN DOOR SEAL, and MASTER CAUTION lights remained off. Immediately after departure, those lights illuminated. The PM requested a return. The pilot flying (PF) began maneuvering when the MED opened in flight. The crew declared an emergency but could not hear ATC due to noise; they were contacted via light gun signals. Upon landing, the open MED contacted the runway but remained attached.
Examination revealed substantial damage to the MED and surrounding airframe.
Aircraft Information
According to FAA records, the airplane was manufactured in 1986 and registered to a corporation in 2013. The most recent continuous airworthiness inspection was a 1000-hour "C" inspection on June 22, 2015, at 8668.6 hours total time. During that inspection, a mechanic initialed the "Passenger/Crew Door – Check."
The MED was a semi-plug-type door with 10 stop pins, locking cams, a mechanical stirrup, and a handle. Door locking involved vertical translation and rotation, inserting stop pins into stop pads, and rotating locking cams. The handle pin would contact and displace a spring-loaded stirrup; when released, the stirrup secured the handle. The spring-loaded stirrup had to be manually displaced to unlock. A pressure interlock prevented operation when pressurized. Air springs provided a "self-locking" feature: they would move the handle to the locked position if released 10-15 degrees before contacting the stirrup. The air springs were a maintenance item in the Passenger/Crew Door check.
Three micro-switches monitored door position: the seal pressure switch (amber DOOR SEAL annunciator), the door switch, and the door lock switch (red CABIN DOOR annunciator).
Personnel Information
The pilot flying held an ATP certificate with type ratings for G-100, IA-1125, and IA-JET. His first-class medical was issued September 2014. He reported 3,265 total flight hours, 273 in type.
The pilot monitoring held an ATP certificate with type ratings for EMB-505, G-100, and IA-1125. His first-class medical was issued June 2015. He reported 5,724 total hours, 182 in type.
Meteorological Information
At 2054, BWI reported calm wind, few clouds at 6,000 feet, scattered at 25,000 feet, 10 miles visibility, temperature 23°C, dew point 13°C, altimeter 29.95 inHg.
Flight Recorders
The cockpit voice recorder was auditioned. It revealed that while taxiing, the PF noted "cabin door is closed." The before departure checklist was completed without anomalies.
Tests and Research
The door was examined at the manufacturer. When the locking mechanism was engaged into the stirrup, the door remained locked. However, the air-spring self-locking feature did not function when tested: the handle could be released at any point and remain in place; the air-springs exhibited no output forces. When replaced with mock-up air-springs, the self-locking feature operated normally.
The CABIN DOOR annunciator switch and wiring were tested. No anomalies prevented normal operation. The switch deactivated (light off) when the locking mechanism rested on the stirrup but was not fully engaged. The switch activated (light on) when the handle was not in contact with the stirrup.
No anomalies with the door securing mechanism were found that would have precluded normal operation.
Additional Information
The Airplane Flight Manual Before Taxiing checklist required: "CABIN DOOR – CLOSED; physically verify that two door locks and stops are in place and handle pin is latched and locked. CABIN DOOR (red) light - OUT."
The Quick Reference Handbook Before Taxiing checklist similarly required physically verifying locks and that the amber annunciator was out.
The Maintenance Manual 1000-hour inspection included: "Passenger/Crew Door – Check" (lock door, slowly release handle 10-15 degrees before locking position, verify inner air-springs lock automatically, ensure handle cannot be rotated unless stirrup depressed), "Door Warning System – Operational Test" (verify annunciator lights extinguish), and "Passenger/Crew Door Microswitch – Adjustment/Test."