N516DA

1.1 HISTORY OF FLIGHT

On March 13, 2000, about 2006 Pacific standard time, Delta Airlines flight 1972, a Boeing 727-232, N516DA, had the right main landing gear fail to fully extend prior to landing at San Francisco, California. Delta Airlines, Inc., was operating the airplane as a scheduled domestic passenger flight under the provisions of 14 CFR Part 121. The airline transport pilot captain, first officer (FO), second officer (SO), 4 flight attendants, and 70 passengers were not injured. The airplane sustained damage to secondary structure. The flight departed San Francisco about 1835 as a nonstop to Salt Lake City, Utah. Visual meteorological conditions prevailed, and an instrument flight rules (IFR) flight plan had been filed.

This was the second leg of the day in the airplane for this crew; their first leg was from Dallas, Texas, to San Francisco. The SO completed walk around inspections at Dallas and San Francisco and noted no discrepancies.

The captain was hand flying the airplane in the initial takeoff climb, and selected landing gear up passing through 300 to 500 feet above ground level (agl). The red "doors" light illuminated on the front panel and the amber right main gear door light illuminated on the second officer's panel. The crew notified air traffic control, briefed the passengers, and climbed the airplane to 5,000 feet on vectors to a safe maneuvering area over the ocean. The crew completed their checklists; the captain gave the FO control of the airplane, and briefed the flight attendants. He did not dump fuel to allow maximum time to analyze the situation.

The captain contacted Delta maintenance in Atlanta to discuss all available options. The crew completed the emergency procedures in their flight manuals, and discussed cycling the landing gear. Delta procedures did not allow the pilot to cycle the landing gear in this situation with the intent to avoid more complications. The captain selected landing gear down, and green lights illuminated for the nose gear and left main gear, while a red light illuminated for the right main gear. The red "doors" light on the front panel and the amber right main gear door light on the second officer's panel remained illuminated. The SO, who went into the cabin to view the landing gear position through a porthole, reported seeing the clamshell door, the wheel canted down about 10 to 15 degrees, and the ground. The crew attempted manual extension procedures several times with no movement of the wheel. They made preparations for a partial gear landing. The checklist included briefing for an emergency evacuation.

The captain declared an emergency with air traffic control.

The captain called the lead flight attendant up to the cockpit, and explained the problem. The lead flight attendant briefed the other flight attendants. The flight attendants reviewed their procedures and briefed the passengers and divided the required duties.

The flight crew depressurized the cabin. After announcing their intentions to the passengers, the flight crew shook the airplane to try and loosen the gear. The attempt was unsuccessful. The captain resumed control of the airplane, returned to the airport, and flew an instrument landing system (ILS) to a visual approach. He acquired the airport at the outer marker. He aligned the airplane slightly left of centerline in case the airplane pulled to the right. He pulled about 20 degrees of spoiler for better roll authority, and did not use the thrust reversers. He applied left aileron to hold the right wing up as long as possible, and the wing stayed off of the ground until about 110 knots. He used slight pressure on the left brake, and said that the airplane went straight ahead. The airplane stopped smoothly about 3 feet right of centerline. The tower said that there were no signs of fire, and the captain noticed crash and rescue personnel around the airplane. The captain ordered an evacuation, completed the evacuation checklist, and pulled the T handles. The flight crew then assisted with the evacuation.

1.2 DAMAGE TO AIRCRAFT

The right wing leading edge slats, right flaps, right wing tip, and right main gear doors sustained damage.

1.3 PERSONNEL INFORMATION

1.3.1 Captain

The captain held an airline transport pilot certificate with an airplane multiengine land rating. He held type ratings for the DC-9, B737, and B727. He also held a certified flight instructor's (CFI) certificate with ratings for airplane single engine land and glider. He held a first-class medical certificate issued on January 21, 2000, with no limitations or waivers. He had 19,021 hours total time; 1,695 hours in this make and model, and 183 hours logged in the last 90 days.

1.3.2 First Officer

The first officer held a commercial pilot certificate with multiengine land and instrument ratings. He held a first-class medical issued on October 18, 1999, with no limitations or waivers. He had 9,979 hours total time; 6,231 were in this make and model with 171 hours logged in the last 90 days.

1.3.3 Second Officer

The second officer held an airline transport pilot certificate with an airplane multiengine land rating. He had type ratings for the CL65 and EMB120. He held a flight engineer's certificate. He held a first-class medical certificate issued on October 18, 1999, with no limitations or waivers. He had 8,095 hours total time.

1.4 AIRCRAFT INFORMATION

1.4.1 Airframe

The airplane was a Boeing 727-232, serial number 21432. The operator reported a total airframe time of 63,246.5 hours. The airplane was maintained on a continuous airworthiness program, and the last inspection occurred on March 8, 2000, approximately 42 hours prior to the mishap. The three engines were Pratt and Whitney JT8D-15A models, rated at 15,000 pounds of thrust each. Serial numbers for engines 1, 2, and 3, respectively, were: 700797, 687501, and 695292.

1.4.2 Landing Gear System

1.4.2.1 Overview

The main gear doors close over the wheel well opening when the landing gear are retracted or extended by the normal hydraulic system. Hydraulic power normally operates the wheel well doors. Mechanical linkage from the landing gear operates the wing doors, which close over the shock strut aperture only when the gear is retracted. A safety bar mechanism completely opens the wheel well doors upon manual extension or with a malfunction of the power operating system. There is a release mechanism, which allows opening of the doors for servicing. Only hydraulic action closes the wheel well doors.

1.4.2.2 Main Gear Doors

The doors consist of two parts, an inner door hinged to the keel beam and an outer door hinged to the outer edge of the inner door. The door actuator and actuation beam connect to a large bracket on the inner door. The outboard end of the actuator pivots in the actuator beam. The actuator beam connects to the structure via a swinging link and an adjustable rod. Hinges raise the outer door when its inner door closes. Each end of the outer door has a radius rod installed between the outboard edges of the door, which raises the outer end into position as the door closes. The gear sequence control rod attaches to a bracket mounted on the aft end of the inner door near the hinge line.

1.4.2.3 Wing Doors

The wing doors are hinged to the lap inner rail. An actuator rod is attached to a support fitting mounted on the door center rib. The opposite end of the actuator rod attaches to the shock strut. A hook mechanism supports the wing doors in the closed position, and prevents them from drooping during high-speed flight. Correct sequence of operation is ensured since the main gear doors open and close only when the main gear conveying the wing doors are locked in the up or down positions.

1.4.3 Safety Bar Mechanism

The door safety bar mechanism is in each main gear wheel well. It will completely open the wheel well doors if they are not fully open when the main landing gear extend. The mechanism includes a safety bar, a pushrod, a door drive rod, and a bellcrank. The safety bar and the bellcrank pivot on fittings attached to the wheel structure. Both the pushrod and the door drive rod can be adjusted. Each safety bar hinges to the keel bean and projects horizontally when the wheel well doors close. The pushrod connects the safety bar to the bellcrank arm. The door drive rod connects the door to the door drive arm. The door and safety bar operate simultaneously.

During normal operation of the wheel well doors, the inboard doors raise and lower the safety bar. The safety bar rises to a horizontal position when the doors close, and lowers clear of the main gear retraction path when the doors are fully opened. Door movement is transmitted to the safety bars through the door drive rod, bellcrank, and pushrod. If the doors do not open or fail to open fully when the landing gear is extended, the descending main gear tire contacts the safety bar, which will be forced down by the weight of the gear. The movement transmits through the pushrod to the bellcrank, which rotates and opens the doors by pushing down on the door drive rod.

1.5 METEOROLOGICAL INFORMATION

A routine aviation weather report (METAR) for San Francisco was issued at 1956. It stated: skies scattered at 800 feet; visibility 10 miles; winds from 260 degrees at 18 knots; temperature 53 degrees Fahrenheit; dew point 52 degrees Fahrenheit; altimeter 30.18 inches of mercury.

1.6 COMMUNICATIONS

The airplane was in contact with Bay Terminal Radar Approach Control (TRACON) throughout the departure and approach.

1.7 AIRPORT INFORMATION

The airport/ facility directory, southwest U. S., indicated that runway 28 R was 11,870 feet long and 200 feet wide. The runway surface was grooved asphalt.

1.8 Flight Recorders

A National Transportation Safety Board specialist performed a readout and evaluation of the Digital Flight Data Recorder (DFD...