...lots of intelligent remarks, but surprisingly alarming things can happen even well above 10kt. I doubt that many of us would intuitively have expected the following to have resulted from an uncontained number one on a trijet...
DC-10's three engines damaged by take-off uncontained failure
Chris Kjelgaard, Washington DC (11May00, 20:51 GMT, 928 words)
A McDonnell Douglas DC-10-30 operated by Continental Airlines experienced an uncontained engine failure that damaged all three of the aircraft's engines and caused substantial damage to the airframe and landing gear, while the DC-10 was taking off from Newark Airport on 25 April.
According to the preliminary report issued by the US National Transportation Safety Board (NTSB), none of the three pilots, 11 flight attendants and 220 passengers on board was injured in the take-off incident, which led the DC-10's pilots to complete the take-off but return to Newark for an emergency landing.
The aircraft involved in the incident was registered N39081 and according to Airclaims' CASE database is a DC-10-30 built in 1973 for Alitalia but operated by a host of airlines since 1983.
Operators have included Aeromexico; Skyjet; Okada Air; Aerocancun; Excalibur Airways; Caledonian Airways; VIASA; and TAESA. However, many of these carriers wet-leased the aircraft from Skyjet, which operated the aircraft from April 1995 until March 1997.
Owned by the CIT Group, the aircraft had begun its take-off roll in visual meteorological conditions at 19:42 local time on 25 April when the DC-10's number one engine suffered an uncontained engine failure at take-off decision speed (V1).
Scheduled to operate Continental's Flight CO60 to Brussels, the DC-10 had experienced normal engine start-up and taxi operations for the flight, the captain briefing the flightdeck crew during the taxi on procedures in case of engine failures and non-rejected take-off situations.
The NTSB report says the captain lined the DC-10 up on Newark's runway 04L and then applied take-off power slowly and smoothly.
However, quoting from flight crew reports, the NTSB report says that the crew heard a loud explosion at V1. At the same time a white 'engine fail' warning light illuminated in front of the captain and the N1 (fan blade revolutions) measurement for the number 1 engine dropped by 30%.
At that point the measurements from the aircraft's number 2 and number 3 engines appeared to be at their normal take-off settings and the captain continued the take-off. However, after raising the landing gear a red, left main landing gear warning light illuminated on the front panel.
The DC-10 turned to a heading of 010° and continued to climb slowly to 3,000ft. During the climb an airframe vibration developed and the crew started to trouble-shoot the problem after the aircraft levelled off, finding that when they reduced the throttle for the number 3 engine to produce an N1 reading of about 25% the vibration disappeared.
The crew kept both the number 1 and number 3 engines at N1 settings of about 25% for the remainder of the flight, dumping about 41,000kg (90,000lb) of fuel to allow an emergency landing at Newark.
During the vectoring for the return to Newark they ran checklists for conditions of one engine inoperative and two engines inoperative, preparing data cards for both situations.
The captain flew the ILS glideslope down to a full-stop landing on runway 04R, the aircraft's ACARS unit recording it landing safely at 20:16.
However, after the stop the brakes would not release so the crew shut the DC-10's engines down on the runway and passengers and crew were disembarked through the main doors, the aircraft later being towed to a ramp.
The NTSB report quotes the captain of the aircraft as saying that the skilled use of cockpit crew resource management by both the flightcrew and the cabin crew was a major factor in the successful handling of the emergency.
Later examination of the DC-10 revealed that all three engines were damaged.
The low-pressure turbine case of the number 1 engine was breached in the vicinity of the second-stage nozzles, the breach extending from approximately the 3 o'clock to the 9 o'clock position and about the width of the second-stage nozzle segments. All of the segments were missing from the engine, each segment consisting of six nozzle blades.
Nine of the 16 nozzle segments were recovered intact and additional portions of segments were found to produce a total recovery of about 85% of the nozzle blades.
The majority of the nozzle material was found on the departure runway but one segment was found in the DC-10's left main landing gear wheel well.
One of the eight anti-rotation nozzle locks was recovered, with its threaded stud sheared from the plate and the engagement tangs exhibiting wear and damage.
The number 1 engine's first-stage low-pressure turbine blades had minor trailing edge airfoil damage, while the second-stage low-pressure turbine blades showed circumferential rub marks on the inner platform leading edge and on the airfoils near the blade root.
Two fan blades in the number 2 engine exhibited leading edge damage, while all fan blades in the number 3 engine had leading edge damage consisting of tears, rips and material loss.
Pieces of fan blade and material similar to that of the second-stage nozzles from the number one engine were found imbedded in the engine inlet acoustic panels.
The front inboard tire of the left main landing gear was ruptured and the front outboard tire exhibited tread separation but remained inflated.
Inspection of the aircraft revealed impact marks on the outboard side of the left - number 1 - engine pylon; the left wing outboard flap; the underside of the fuselage; the left main landing gear access door; the left side of the fuselage aft of the left wing; and a right-wing panel outboard of the flap actuator housing.
The number 1 engine had had upgraded nozzle locks installed in 1997, as called for in the manufacturer's service bulletin number 721082.
Source: Air Transport Intelligence news