# NTSB DEN03IA147: Beech 1900D, N192GL, Denver, CO, August 24, 2003 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: August 23, 2003, 19:19 local (Aug 24, 2003, 01:19 UTC) - Place: Denver, CO - Coordinates: 39.858612, -104.666946 - Nearby events: https://openairdocs.org/map.md?lat=39.8586&lon=-104.6669&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 16 uninjured - Status: Completed, report February 5, 2004 - Report: Approved by Office Director - Parties: Federal Aviation Administration, Great Lakes Aviation, Limited, Raytheon Aircraft Company - NTSB case key (mKey): 57757 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN03IA147 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/57757/pdf - Page: https://openairdocs.org/ntsb/DEN03IA147 ## Probable cause the first officer's improper preflight preparation in failing to ensure the cabin airstair door was fully locked and secure. Factors relating to the incident were the cabin airstair door handle not being fully secure and the forward cabin door warning light not illuminating until the airplane was in flight. ## Analysis The first officer reported that as part of the first flight of the day, he performed the cabin/cargo door checks. He said, "All checks of the cabin and cargo door circuitry appeared normal." The first officer said that the airstair door operated normally during the three previous flights that day. He reported that on the incident flight, he "did not note any abnormalities as far as the operation/locking of the forward airstair door." He said that the cabin door annunciator light went out as normal after closing and locking the cabin door. He and the captain verified that the doors were closed and the annunciator lights were out. The captain reported that approximately 5 minutes into the flight and passing 8,000 feet msl, the cabin door warning light illuminated. The captain said they ran the checklist, which directed the passengers to ensure their seat belts were fastened. The captain said he directed the first officer to tell approach control that they were returning to the airport. The captain said they did not declare an emergency at that time. The captain said that approximately 2 minutes after the cabin door warning light illuminated, he initiated a 20 to 25 degree bank left turn to take them back to the airport. During the turn, the captain said he heard a pop and the cabin door came open causing damage to the door, doorframe, and left propeller. The captain said they declared an emergency and landed with the cabin door open. An examination of the cabin airstair door showed no anomalies with the locking mechanism and circuitry. An examination of the door sensor to the forward cabin door warning light showed that the door handle could be placed in a position where the door's pressure lock plunger was just engaging the latch plate, but had not dropped into the "keyhole," and the warning light would go out. When moving the handle through the closed position so that the handle could no longer move forward, the pressure lock plunger would fully engage in its "seated position" and the warning light would go out. ## Factual narrative HISTORY OF FLIGHT On August 23, 2003, at 1919 mountain daylight time, a Beech 1900D, N192GL, owned by Great Lakes Aviation, Limited, and operating as Great Lakes Airlines Flight 7079, sustained minor damage when the cabin air stair door opened during climb, approximately 15 nautical miles east-southeast of Denver, Colorado. Cabin pressure was subsequently lost. The crew declared an emergency and made an uneventful landing at Denver International Airport (DEN), Denver, Colorado. The airline transport certificated captain, first officer, and 14 passengers were not injured. Visual meteorological conditions prevailed at the time of the incident. The scheduled domestic passenger flight was being conducted on an instrument flight rules flight plan under the provisions of Title 14 CFR Part 121. The flight from DEN to Santa Fe, New Mexico, originated at approximately 1910. The first officer reported that as part of the first flight of the day, he performed the cabin/cargo door checks. He said, "All checks of the cabin and cargo door circuitry appeared normal." The first officer said that the air stair operated normally during the three previous flights that day. He reported that on the incident flight, he "did not note any abnormalities as far as the operation/locking of the forward air stair door." He said that the cabin door annunciator light went out as normal after closing and locking the cabin door. He and the captain verified that the doors were closed and the annunciator lights were out. After completing the taxi checklists and before takeoff checklists, they were instructed to taxi to runway 17L. The first officer said that at no time during the taxi did any warning lights illuminate. The captain reported that approximately 5 minutes into the flight and passing 8,000 feet mean sea level (msl), the cabin door warning light illuminated. The captain said they ran the checklist, which directed the passengers to ensure their seat belts were fastened. The captain stated he directed the first officer to tell Denver Approach Control that they were returning to the airport. The captain said they did not declare an emergency at that time. The captain reported that approximately 2 minutes after the cabin door warning light illuminated, he initiated a 20 to 25 degree bank left turn to take them back to the airport. During the turn, the captain said he heard a pop and the cabin door came open. They declared an emergency at that time. The captain said they landed with the cabin door open. AIRCRAFT INFORMATION The airplane was a Beech 1900D passenger liner, serial number UE-192, owned and operated by Great Lakes Aviation, Limited, and used for carrying passengers on scheduled, domestic flights. The airplane was being maintained under a continuous maintenance program. The most recent inspection of the airplane was done on August 19, 2003. At that time, the airplane had 17,471.9 total hours. At the time of the incident, the airplane had 17, 493.7 total hours. PERSONNEL INFORMATION The captain held an airline transport pilot certificate with single and multiengine land, and instrument airplane ratings. The captain also held a flight instructor certificate with a single engine land rating. The captain successfully completed a company flight proficiency check on July 13, 2003. The captain reported having 2,850.3 total flying hour; 2,477.3 hours were in Beech 1900s. The captain held a first class medical certificate dated May 7, 2003. The certificate showed no limitations. The first officer held a commercial pilot certificate with single and multiengine land, and instrument airplane ratings. The first officer also held a flight instructor certificate with single and multiengine land and instrument airplane ratings. The first officer successfully completed a company flight proficiency check on December 1, 2002. The first officer reported having 1,541 total flying hours with 654 hours in Beech 1900s. The first officer held a first class medical certificate dated August 20, 2003. The certificate showed the following limitation: "Holder shall wear lenses that correct for distance vision and possess glasses that correct for near vision. WRECKAGE AND IMPACT INFORMATION The airplane was examined at Denver, Colorado, at 2200. The airplane's cabin air stair door was hyper-extended in the open position. The door's aft upper support cable was snapped approximately 51 inches outboard of the cable attachment at the top aft corner of the door. The cable was unraveled at the fracture showing evidence of overload. The cable sheathing was pulled apart. The "snubber" arm at the front of the door was bent downward 90-degrees. The snubber cable was broken out at the bolt attachment at the end of the arm. The top 6 inches of the cable were missing. The remaining cable was fractured, kinked, and unraveled. The door hydraulic cylinder arm was in the "door closed" position. The door hinge, located along the bottom of the door, was bent outward and aft. The air stair door was bent outward in two places; the first, approximately 21 inches outboard of the hinge, and the second, approximately 46 inches outboard of the hinge. The top two steps on the air stair were cracked at the bases. The inside door handle was observed in the unlocked and open position. The door handle was bent laterally forward approximately 10 degrees. The door's eight cam locks showed no damage. The door frame aft inside bulkhead was cracked at the upper outside corner. The left propeller showed damage to 2 of its 4 blades. One blade had a 3/4-inch nick in the blade tip. The second blade showed a 1/8-inch nick in the leading edge near mid-span. Flight control continuity was confirmed. A field examination of the door locking mechanism and cabin door warning light showed no anomalies. The cabin door, flight data recorder, and cockpit voice recorder were retained for further examination. TESTS AND RESEARCH The cabin air stair door was examined at Great Lakes Aviation, Limited, Cheyenne, Wyoming on August 26, 2003. Company maintenance records showed the door had 2,240.9 hours total time and 2,853 cycles. The manufacturer directs the door's overhaul at 12,000 hours or 16,000 cycles. The door handle and locking mechanism were tested. When the handle was moved to the locked position and pushed to the point where no further movement was noted, the 8 cam locks rotated approximately 180-degrees and the pressure lock plunger engaged the latch plate, locking the handle in place, as specified by the manufacturer. The latch cables and turnbuckles moved freely and showed proper tension. An examination of the door sensor to the forward cabin door warning light on the annunciator panel showed that the door handle could be placed in a position where the door's pressure lock plunger was just engaging the latch plate, but had not dropped into the "keyhole," and the warning light would go out. When moving the handle through the closed position so that the handle could no longer move forward, the pressure lock plunger would fully engage in its "seated position" and the warning light would go out. Backward pressure was then applied to the handle. With the pressure lock plunger engaged, the handle could not be moved from the closed position until the door latch-release button was depressed. The manufacturer's specifications for maintenance of the air stair door and pressure lock switch states, "The pressure lock plunger rides in the keyway at a point 0.04 inch or less from where the plunger drops into the keyhole ... Adjust the pressure lock switch so that it closes, illuminating the FWD CABIN DOOR light, with the plunger pulled up between .03 and .09 inch from its fully seated position." This test was performed on several other Great Lakes Aviation, Limited, Beech 1900 airplanes. In those tests, the same anomaly could not be ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Miscellaneous/other, climb - to cruise - preflight planning/preparation - improper, copilot/second pilot (cause) - door,entrance stair - not secured (contributing factor) - annunciator panel light(s) - other (contributing factor) - door,entrance stair - open ## Aircraft - Registration: N192GL (not matched to a registry record) - Reported make and model: Beech 1900D - Category: Airplane - Serial number: UE-192 - Airframe hours: 17493.7 - Engines: Pratt & Whitney PT61-67D 1279 horsepower turbo prop; Pratt & Whitney PT6A-67D 1279 horsepower turbo prop - Damage: Minor damage - Flight: Part 121 - Registered owner: Great Lakes Aviation, Limited - Airworthiness certificate: Standard, Transport - Last inspection: Continuous airworthiness, August 19, 2003, 21.8 hours before - Departed: DEN, Denver, CO - Destination: SAF, Santa Fe, NM - Flight plan: IFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 31; injuries: none; airline transport, flight instructor; airplane ratings: single-engine land, multi-engine land, single-engine sea; instrument ratings: airplane; medical: class 1; last flight review July 13, 2003; seat: left; flight hours: 2,850 total, 2,477 in this make and model, 834 as pilot in command, 224 in the last 90 days, 59 in the last 30 days, 6 in the last 24 hours - Co-pilot; age 24; injuries: none; commercial, flight instructor; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--w/ waivers/lim; last flight review December 1, 2002; seat: right; flight hours: 1,541 total, 654 in this make and model, 761 as pilot in command, 244 in the last 90 days, 76 in the last 30 days, 6 in the last 24 hours ## Weather - Conditions: Visual (VMC), Dusk - Wind: 200° at 18 knots - Visibility: 10 statute miles - Lowest ceiling: 9,500 ft overcast - Temperature: 73 °F, dew point 57 °F - Altimeter: 30.14 inHg - Observed at: DEN, 10 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20030823021209A](https://openairdocs.org/incident/20030823021209A), Aug 23, 2003: Beech 1900D, Denver, CO, Substantial damage. (-23) Lakesair 779, Denver to santa fe, departed den and door came open in flight. Declared emergency, returned to den and landed RY26. ARFF responded to… From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.