AAIB investigation to Beech 400A, N709EL

1� Crown copyright 2024 All times are UTC AAIB Bulletin: N709EL AAIB-28705 Serious Incident Aircraft Type and Registration: Beech 400A, N709EL No & Type of Engines: 2 Pratt & Whitney Canada JT15D turbofan engines Year of Manufacture: 1992 (Serial no: RK-52) Date & Time (UTC): 7 October 2022 at 1100 hrs Location: Newquay Airport, Cornwall Type of Flight: Private Persons on Board: Crew – 2 Passengers – 1 Injuries: Crew – None Passengers – None Nature of Damage: Damage to mainwheel tyres Commander’s Licence: Airline Transport Pilot’s Licence Commander’s Age: 40 years Commander’s Flying Experience: 5,263 hours (of which 2,692 were on type) Last 90 days – 150 hours (of which 30 on type) Last 28 days – 47 hours (of which 4 on type) Information Source: AAIB Field Investigation Synopsis Immediately after touchdown the flight crew noticed the deceleration was greater than normal. Reverse thrust and speed brakes were applied, and as the aircraft slowed below about 50 kt the aircraft started to drift towards the right side of the runway. A combination of weathercocking into the wind and applying left pedal brought the aircraft back to the runway centreline where it came to rest angled about 45° to the left of the centreline, with the mainwheel tyres deflated and the brakes seized. The rapid deceleration on touchdown was caused by either the tyres having already deflated due to the fuse plugs having melted, or the brakes being seized, or a combination of both. This was the result of the brakes having been heated during the takeoff run because the parking brake had been left on with partial pressure applied. The lack of a light or caption to indicate that the parking brake is on, or an aural or visual warning that the parking brake is on when takeoff power is applied, may have contributed to the incident, as may have the lack of a ‘release parking brake’ item in the ‘Before Takeoff’ checklist. One Safety Recommendation is made to the aircraft manufacturer regarding the ‘Before Takeoff’ checklist. 2� Crown copyright 2024 All times are UTC AAIB Bulletin: N709EL AAIB-28705 History of the flight During the takeoff roll from East Midlands Airport the commander reported that the acceleration seemed normal through 80 kt, but then there was a hesitation in acceleration at about 95 kt. He felt there might be extra drag on the nosewheel, but the aircraft rotated and climbed normally after liftoff. The crew completed the after-takeoff checks and there were no indications of abnormalities. The commander thought the reduced acceleration at about 95 kt might have been caused by possible loss of nosewheel tyre pressure, because the tyre had been replaced prior to flight. Another possibility considered was a gust of wind during takeoff as the wind was 22 kt gusting 33 kt. He discussed these theories with the co-pilot. Prior to the descent, the commander was scanning the flight deck and noticed that the parking brake handle on the lower left side of the instrument panel was not fully pushed in. He pushed it in, which required some force but no more than he sometimes experienced when disengaging the parking brake on the ground after it has been applied after a landing. He then realised that the reduced acceleration was probably caused by the parking brake remaining on, with partial brake pressure locked in the system, causing the brakes on the main wheels to remain applied during the takeoff. He considered the possibility that the brakes had then become heated during the takeoff roll due to the friction in the brake pack as the wheels attempted to rotate against the brakes. The heat generated may then have caused the thermal relief plugs in the wheel hub to melt and release main wheel tyre pressure. He did not recall setting the parking brake at the holding point prior to takeoff, but he assumed he probably did. He could not recall if he subsequently pushed the parking brake handle partially in to release or not at all. He reported that a normal amount of break-away thrust was required to leave the holding point and the initial acceleration felt normal, so the brakes could only have been applied with partial brake pressure. The parking brake operates by locking in the pressure applied by the toe brakes, so applying a small amount of toe brake pressure will provide a small amount of parking brake pressure. The commander reported that there was a slight uphill gradient at the holding point and without brake pressure applied idle thrust alone would overcome the gradient and cause the aircraft to move forwards, so he thought it likely that he had only needed to apply a small amount of brake pressure to prevent the aircraft rolling forward. The flight crew briefed for the possibility of loss of tyre pressure on landing. The landing gear was lowered early to allow for additional cooling of the brakes, although he realised that this would have no effect if the fuse plugs had already melted. The aircraft’s Quick Reference Handbook (QRH) did not provide any guidance for this situation. At their destination of Newquay Airport the landing distance available was 8,000 ft which was within the calculated distance required of 3,300 ft, and the weather was suitable. They planned to touch down close to the runway threshold to maximise the runway available. 3� Crown copyright 2024 All times are UTC AAIB Bulletin: N709EL AAIB-28705 The ILS approach to Runway 30 at Newquay was normal, and the aircraft touched down close to the runway threshold. The wind at the time of the landing was from 240° at 21 kt. Immediately, the commander noticed the deceleration was greater than normal. Reverse thrust and speed brakes were applied, and as the aircraft slowed below about 50 kt the aircraft started to drift towards the right (downwind) side of the runway. A combination of weathercocking into the wind and applying left pedal brought the aircraft back to the runway centreline where it came to rest angled about 45° left of the centreline. The flight crew shut down the engines and advised ATC they were evacuating on the runway. The crew and passenger then exited via the cabin door. The mainwheel tyres were found fully deflated and there was smoke emanating from them, but there was no fire. The airport fire service was on the scene shortly thereafter. Recorded information The aircraft was fitted with a Cockpit Voice Recorder (CVR) which was downloaded at the AAIB. The audio quality of the two flight crew channels was poor, rendering most of the speech unintelligible. Tests on the CVR did not reveal any faults so it indicated an issue with the aircraft’s system. The operator re-installed the CVR and carried out the normal maintenance procedure checks which did not reveal any issues. However, the maintenance procedure does not require listening to a sample recording. The AAIB suggested this to the operator, but the aircraft was in the process of being sold so this was left to the new owners. Aircraft information The Beech 400A (later models were renamed the Hawker 400) is a light business jet with an MTOW of 7,303 kg (Figure 1). It has capacity for seven to nine passengers. Figure 1 Incident aircraft Beech 400A after it came to rest off the runway centreline 4� Crown copyright 2024 All times are UTC AAIB Bulletin: N709EL AAIB-28705 The parking brake handle is located on the lower left side of the instrument panel (Figure 2). The parking brake is set by pulling the handle fully out and depressing the toe brakes. The hydraulic brake pressure applied by the toe brakes is then locked in the system when the toe brakes are released. Accordingly, the pressure applied when the parking brake is set is not a fixed value but varies depending on the instantaneous pressure applied at the toe brakes when the parking brake handle is pulled. Pilots can therefore set an intermediate (partial) pressure between zero and the maximum achievable brake pressure. The parking brake is released by pushing t

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AAIB investigation to Beech 400A, N709EL

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