Safety experts are calling on the US Federal Aviation Administration to substantially heighten oversight of Allegiant Air after a missing nut led a McDonnell Douglas MD-83’s elevator to jam on 17 August.
The jam caused the aircraft’s nose to rotate prematurely during takeoff, prompting the pilots to abort.
Though the aircraft returned safely to the gate, experts describe the malfunction as a serious concern that elicits memories of a number of fatal airline crashes.
“Any time you have a flight control issue with any aircraft, especially a commercial airliner, it is a big concern for the safety and sanctity of the flight,” Gregory Feith, former senior air safety investigator at the National Transportation Safety Board (NTSB) tells Flightglobal. “What is going on? This is not the first problem Allegiant has had in the last 18 months.”
“This is one of those items that you don’t mess around with,” says John Goglia, a former NTSB member. ”I hope that the FAA ups the ante – that they bring in some good people and provide some oversight, so we don’t see a repeat of ValuJet.”
The Allegiant incident occurred as flight 436, bound for Peoria, Illinois, rolled down the runway at Las Vegas International airport the evening of 17 August.
As the aircraft gained speed, the nose lifted off the ground earlier than it should have, and the aircraft remained nose-high despite efforts by the pilots to adjust the flight controls, according to the FAA and a report from Bloomberg.
The pilots aborted the takeoff and returned to the gate.
“During the take-off roll, the pilots recognised a malfunction in the flight control system and aborted the take-off,” says Las Vegas-based ultra-low-cost carrier Allegiant in a statement. “Upon inspection, it was discovered that the left elevator boost actuator had become disconnected.”
The FAA says a missing nut caused the malfunction.
“A preliminary investigation found that a nut on a component that moves the left elevator had fallen off, causing the control surface to become jammed in the up position,” the safety regulator says in a statement.
Allegiant declined to make an executive available to discuss the incident, but says it reported the event to the FAA and NTSB. It also inspected its entire MD-80 fleet and returned the aircraft involved in the incident to service after repairs, it says.
“The investigation is ongoing, and we are cooperating with the FAA,” adds Allegiant.
Feith says the incident could have ended in disaster had the pilots not discovered the issue while time remained to abort the take off, noting that the aircraft could have been uncontrollable once airborne.
“They were fortunate,” he says.
Goglia calls such a flight control failure “very, very rare”. “The passengers on the airplane are extremely lucky,” he adds.
Details of the incident led both former investigators to recall other deadly air crashes resulting from flight control problems, including Alaska Airlines flight 261, an MD-83 that crashed into the Pacific Ocean on 31 January 2000, killing 88 passenger and crew.
The NTSB determined that the pilots lost pitch control after a nut in the jackscrew assembly failed due to maintenance shortcomings.
Then on 16 February 2000, an Emery Worldwide Airlines Douglas DC-8 freighter crashed shortly after takeoff from Sacramento, killing three crew.
The NTSB’s report said the crew lost control due to disconnection of the right elevator control tab, citing failures to inspect an attachment bolt.
“They fought the aircraft, and lost,” says Feith of the Emery crew.
Allegiant’s 17 August aborted takeoff follows a rash of emergency landings and other flight incidents experienced by the carrier in recent months, some of which have spurred FAA investigations.
Allegiant aircraft made a number of emergency landings in June, July and August, according to reports.
And on 23 July pilots of an Allegiant MD-80 declared a fuel emergency before landing at Fargo.
The airline insisted that the aircraft was not close to running out of fuel, but the event apparently occurred because the pilots were unaware that the Fargo airport was closed to commercial traffic at the time.
Feith calls the number of such events “inordinate”.
“Those are the warning flags that the FAA is supposed to be paying attention to,” says Goglia.
Goglia adds that the frequency of Allegiant’s issues remind him of the string of issues suffered by now-defunct ValuJet, which was co-founded by Maurice Gallagher, Allegiant’s chief executive.
From 1 January to 10 May 1996, more than 50 ValuJet flights returned after takeoff due to maintenance issues, Goglia says.
Then on 11 May 1996, an oxygen canister ignited on ValuJet flight 592, causing the DC-9 to crash into Florida’s Everglades, killing 110 people.
The NTSB faulted ValuJet for poor oversight. It merged with AirTran Airways and dropped the ValuJet name the following year.
“The warning signs are here” with Allegiant, says Goglia. “How many [emergencies] do we have to have.”
Though Allegiant declined to discuss the latest incident, the carrier’s former president Andrew Levy told Airline Business in 2013 that Allegiant was growing at a relatively moderate pace in order to avoid the types of issues that affected ValuJet.
Levy, who also worked at ValuJet, said that airline “went from zero airplanes to 53 airplanes” in two-and-a-half years.
“The reality is we grew too fast,” he said.
By comparison, Allegiant’s fleet increased to 65 aircraft over 12 years, Levy said at the time. “It’s very consciously a different pace.”
Since then, Allegiant’s fleet has expanded to 76 aircraft, including 53 MD-80-family aircraft, seven Airbus A319s, 10 A320s and six 757s, according to the Ascend Fleets database.
The carrier says it expects to brings its number of A320-family aircraft to 25 by the end of the year.
Source: Cirium Dashboard