History of Flight
On April 27, 2009, at 0700 eastern daylight time, a Cessna 402C, registration N769EA, operated by Cape Air/Nantucket Airlines as a scheduled domestic passenger flight under 14 CFR Part 135, sustained minor damage when the left main landing gear collapsed during landing rollout at Nantucket Memorial Airport (ACK), Nantucket, Massachusetts. Visual meteorological conditions prevailed, and a company visual flight rules flight plan was filed. The certificated airline transport pilot and eight passengers reported no injuries. The flight originated from Barnstable Municipal Airport (HYA), Hyannis, Massachusetts, at 0633.
The pilot reported that on final approach to runway 6, he lowered the landing gear. The left main landing gear light did not illuminate, and the landing gear unlock light and hydraulic pressure light remained illuminated. He recycled the landing gear with negative results, informed the tower, and executed a go-around. He completed the "Gear Will Not Extend" checklist and activated the blow down bottle, also with negative results. He then performed the "Landing With Defective Main Gear" checklist and requested ARFF notification. Upon landing, the left main gear collapsed.
Personnel Information
The captain, age 24, held an airline transport pilot certificate with a multiengine land rating and a commercial pilot certificate with a single-engine land rating issued August 13, 2008. He also held flight instructor and ground instructor certificates. He was hired on May 5, 2005, and completed initial operating experience in the Cessna 402 on June 20, 2007. His last Part 135 checkride was January 18, 2009, and last line check on January 26, 2009. He had 3,525 total flight hours, with 2,750 hours in the Cessna 402C and 3,111 hours as pilot-in-command. His first-class medical certificate, issued April 15, 2009, required corrective lenses. Training records were up to date.
Aircraft Information
The Cessna 402C, serial number 402C0303, was a twin-engine airplane with tricycle landing gear manufactured in 1980. It was powered by two Continental TSIO-520-VD fuel-injected 325-horsepower engines. Hyannis Air Service LLC purchased it on January 8, 1999. The last approved aircraft inspection program inspection was completed on April 18, 2009. Total airframe time was 24,161 hours. The left engine had 2,321.6 hours, and the right engine 10.8 hours. The last gear retraction and emergency extension test was on April 16, 2009.
Meteorological Information
The 1628 ACK surface observation reported wind 120 degrees at 9 knots, visibility 10 miles, clear sky, temperature 10°C, dew point 4°C, and altimeter 30.39 inHg.
Wreckage and Impact Information
The airplane came to rest in the grass off the left side of runway 6, and an emergency evacuation was completed. An FAA inspector found that the left main landing gear had collapsed because it did not lock down. The left flap was scraped, the left wing tip damaged, and a dent on the left wing about 8 feet inboard of the left engine from a taxiway light. The left propeller was also damaged. After recovery, maintenance personnel manually extended and locked the left main gear. The airplane was flown to HYA on a special flight permit for further inspection.
A landing gear retraction test duplicated the failure of the left main gear to extend. Hydraulic pressure was present at the extend inlet of the up lock actuator but not at the extend outlet. The up lock actuator retracted correctly, but the up lock hook allowed the gear to fall. Inspection of the extend inlet port revealed a small ball bearing in the wrong position relative to the larger ball bearing, and the small ball bearing was undersized, causing blockage. The up lock and main gear actuators were quarantined.
Disassembly of the up lock actuator at an authorized repair facility found an improperly sized ball bearing that controlled the port opening. The actuator housing, ball spring, and fitting assembly were damaged. The main gear actuator tested within limits.
The operator's Director of Maintenance stated that up lock actuators were condition items overhauled in-house by one individual for over 10 years, who reported never replacing the ball bearings—only O-rings and internal shafts as needed. The actuators were not tracked, and the history of the defective ball bearing was unknown.
Medical and Pathological Information
Toxicology specimens from the captain were analyzed and were negative for amphetamines, opiates, marijuana, cocaine, and phencyclidine.
Test and Research
From April 27, 2008, to April 27, 2009, the FAA conducted 81 maintenance or operation enroute inspections, 207 airworthiness surveillance inspections, 113 operations inspections, and 13 facility inspections of Hyannis Air Service Inc.