Landing gear/indication

What happened

At about 2000 local time on 21 June 2021, the crew of a Gates Learjet Corporation Model 36 aircraft taxied to depart from Nowra, New South Wales. During the taxi, the crew had difficulty turning the aircraft.

After take-off, the crew received an unsafe landing gear indication when the wheels were retracted and in response, elected to extend the landing gear. When the landing gear was extended, the crew observed a normal cockpit indication and returned the aircraft to Nowra. A fly-by inspection revealed that the nose landing gear, while extended, was oriented side on to the direction of travel. Upon touchdown the nose wheel quickly straightened, and the landing roll proceeded without further incident.

After the flight, maintenance engineers inspected the aircraft. Their assessment was that during landing gear retraction, the uplock roller failed to engage the uplock latch because the roller was facing downwards after rotating through 180º during taxi. Prior to landing, the nose wheel was reportedly oriented side-on to the direction of travel. This is likely to have occurred when the crew extended the landing gear and the centring mechanism attempted to correct the orientation of the nose wheel.

Figure 1 shows the normal operation of the nose wheel landing gear when it is retracted. The uplock roller attached to the lower portion of the nose wheel landing gear leg is captured by the uplock latch in the wheel well. This closes a switch which provides the crew with a landing gear up and locked indication in the cockpit.

Prior to the flight, the aircraft’s nose wheel landing gear steering was marked on the maintenance release^[1] with a Minimum Equipment List^[2] (MEL) entry to notify the crew of a known fault with the system. The crew had signed the maintenance release and were aware of the defect. This fault affected the pilots’ ability to manipulate the nose wheel, however, steering was still possible through the use of differential braking. The flight manual specified that while operating with degraded steering performance, tight turns were to be avoided. The difficulty the crew experienced while positioning for take-off is likely due to the castoring lower portion of the nose wheel landing gear arm rotating through 180º to face in the opposite direction.

Figure 1: Normal operation of the nose wheel landing gear uplock

Source: ATSB

Safety action

As a result of this occurrence, the operator has advised the ATSB that they have taken the following safety actions:

• The crew were alerted to the potential risks of the nose wheel being reversed due to sharp turns and the likelihood of experiencing turning difficulties.
• Procedures were introduced to manage a possible reversed nose wheel during taxi.
• Updated guidance was provided regarding the positioning of aircraft for dispatch when nose wheel steering was unserviceable.
• Engineering held a meeting to highlight the importance of correct strut servicing and the identification of potential traps or error points.

Safety message

This incident highlights the importance of adhering to manufacturers’ recommended operating procedures, especially those imposed by Minimum Equipment List conditions. The Civil Aviation Safety Authority publication

Its purpose is not to encourage the operation of aircraft with inoperative equipment. Such operations are permitted only as a result of careful analysis of each item to ensure the required level of safety is maintained.

A thorough understanding of aircraft systems is required for a crew to accurately assess the effect a particular defect has on normal operations.

About this report

Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report and allow for greater industry awareness of potential safety issues and possible safety actions.

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1. Maintenance release: an official document, issued by an authorised person as described in Regulations, which is required to be carried on an aircraft as an ongoing record of its time in service (TIS) and airworthiness status. Subject to conditions, a maintenance release is valid for a set period, nominally 100 hours TIS or 12 months from issue.
2. Minimum equipment list: A document created specifically to regulate the continued operation of an aircraft with inoperative equipment under certain conditions or limitations. /a>

What happened

On 4 May 2020, an Aero Commander 500-S was operating a freight charter flight from Port Lincoln Airport, South Australia with a single pilot on board. During initial climb, the pilot noticed that the landing gear unsafe light did not extinguish after the gear was retracted. The pilot contacted aerodrome ground crew to inspect the aircraft’s landing gear during a low-level fly-by. The ground crew, including an engineer, confirmed that the nose wheel was down but did not appear to be locked.

The pilot requested that emergency services attend the aerodrome for a return landing on runway 01, and continued troubleshooting in accordance with the operator’s standard operating procedures and the aircraft flight manual. The pilot conducted a touch-and-go landing on the rear wheels, which resulted in three green indication lights in the cockpit confirming the gear was down and locked. The crew subsequently conducted a further fly-by inspection where ground crew also confirmed the position of the nose landing gear. The aircraft then landed without further incident.

After an engineer inspected the landing gear, the aircraft taxied off the runway. An inspection of the landing gear system revealed that the nose gear actuator shaft had failed.

Figure 1: Failed nose gear actuator shaft

Source: Aircraft operator

Safety action

As a result of previous similar occurrences, the aircraft operator has advised the ATSB that it has been conducting midlife inspections of the nose landing gear area, as well as additional testing of the actuator during overhauls. Additionally, their entire fleet of Aero Commander 500 aircraft has been fitted with underbelly skid blocks to support the nose in the event of a gear failure.

Safety message

This incident highlights the importance of effective cockpit scans for the early detection of any abnormal situations during flight. In this instance, the pilot identified the fault, took all precautionary measures and communicated clearly with ground crews resulting in a safe landing.

About this report

Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.

What happened

On 17 April 2019 at 1300 Central Standard Time, the pilot of a Cessna 210L aircraft was conducting a chartered passenger flight between Tindal and Hodgson Downs, Northern Territory.

Once established in the circuit area at Hodgson Downs, the landing gear was selected down as the aircraft manoeuvred to land. The pilot confirmed that the gear was down by visually checking the undercarriage was extending, hearing that the gear pump had stopped and identifying three green lights indicating gear down. The pilot continued the approach and completed the pre-landing checks, which included checking the landing gear again on final.

The landing roll felt normal until the aircraft slowed and more weight was applied to the landing gear, at which point the aircraft began to yaw to the right. The yaw was countered with rudder input, however the aircraft continued to yaw right and veered off the runway, coming to rest inside the flight strip.

Once the aircraft was shut down and secured, the pilot evacuated the passengers safely. No one was injured, however the aircraft sustained substantial damage.

Figure 1: Damage sustained to the aircraft after landing

Source: Operator

Engineering Inspection

The engineering inspection revealed one of the gear down indication switches was jammed in the closed position. On L-model Cessna 210 aircraft, when all three switches (left main, right main and nose) are closed, the gear down light is illuminated and the gear pump will stop. Upon further inspection, it appeared the switch was jamming intermittently.

During this incident, the pilot reported that he had lowered the landing gear, completed all checks as appropriate and received three green undercarriage lights. It appeared from the visual check at the time of lowering that the gear was down and locked. It is likely that the left main gear and the nose gear locked before the right main gear, however due to the right main gear switch being stuck in the closed position, the light illuminated and the pump stopped before the right main gear had fully locked in the down position.

Safety action

As a result of this occurrence, the aircraft operator has advised the ATSB that they are taking the following safety actions:

The incident has been examined and debriefed with the pilot and company’s training captains.

A company-wide memo was released regarding the importance of the visual undercarriage checks on final approach. As part of ongoing updates to the company flight crew operating manual, a revised final approach procedure has been included to clearly specify that visual gear checks must be conducted on final approach as part of the ‘UNDERCARRIAGE’ item on the checklist.

Safety message

This incident highlights the importance of pilots being familiar with all aircraft systems. This allows them to be aware of the possible effects of the failure of an interacting or interrelated component in those systems and provides them with a greater understanding of the aircraft’s operation in both normal and emergency situations.

About this report

Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.

What happened

On 31 October 2018 at 1300 Western Standard Time, the crew of a Jetstream Series 3200 aircraft was conducting a revenue passenger transport flight between Williamtown, New South Wales and Canberra, Australian Capital Territory. The crew comprised of a captain and a first officer. The captain was pilot flying (PF) and the first officer was pilot not flying (PNF).

Just after take-off from Williamtown, the landing gear was selected up. The nose wheel landing gear light remained green to indicate that it had not retracted. The two main landing gear did retract, but were slower than usual. The flight crew also heard unusual sounds as the landing gear attempted to retract.

The PF decided to conduct a return to Williamtown airport. The PF took over the radios from the PNF, and requested an amended 3,000 ft level off and to remain on the tower frequency, while the PNF conducted the after take-off checklist. The PF instructed the PNF to open the aircraft Quick Reference Handbook and find the checklist for gear locked down. During this time, the PF communicated with air traffic control, to request a circuit for a return to land at Williamtown.

On approach, the PNF selected gear down. The system did not respond to this selection, and the main gear did not extend. The PF instructed the PNF to check the circuit breaker (CB) for the gear, however the PNF could not reach the CB. The PF reset the CB, after which the main gear extended.

The crew then landed the aircraft without incident.

Engineering inspection

Following the incident, inspection of the landing gear revealed that a solenoid on the landing gear selector valve failed when the landing gear was selected up.

Safety message

This incident highlights the value of effective cockpit resource management in response to unexpected events. The PF effectively delegated multiple tasks to the PNF, which enabled the PF to focus on flying the aircraft and communicating with ATC. The PF effectively used the resources available to him in order to gather more information about the problems with the aircraft, by instructing the PNF to consult the Quick Reference Handbook. CASA outlines the importance of using available cockpit resources, and provides practical steps for doing so, in their Human Factors for Pilots booklet on Teamwork.

This incident also highlights the importance of effective pilot decision making to ensuring safe flight. The PF’s decision to return to Williamtown, soon after he had identified that the landing gear was not performing as expected, reduced the risk of the situation deteriorating. Flight crew are encouraged to identify the hazards and risks they encounter during flight, and to make control decisions to minimise those risks where possible. The FAA provides decision-making guidance to pilots in their Aeronautical Decision Making (ADM) training package.

What happened

On 27 November 2018, a Piper PA-31 was operating a charter flight with one pilot and three passengers on board to Palm Island, Queensland.

After landing, the nose wheel tyre was punctured by foreign object debris (FOD)^[1] on the runway. The nose wheel began to vibrate resulting in the pilot braking with caution and applying back pressure^[2] to alleviate the pressure on the nose wheel. The rubber on the tyre started to disintegrate and the rim of the wheel dug into the soft asphalt, caused by the extremely hot conditions.

The tyre became caught between the rim and the fork of the nose gear, which acted as a brake and rudder causing the aircraft to veer to the right and off the runway resulting in a nose gear failure. The pilot shut down both engines to reduce the possibility of debris becoming projectiles and to minimise damage to the aircraft before both propellers struck the ground unpowered. 

A screw is suspected to have caused the tyre puncture as nuts and bolts were observed during the runway inspection after the occurrence.

Figure 1: Damage sustained to the aircraft after landing

Source: Operator

Safety message

This occurrence highlights the importance of carrying out regular runway inspections as FOD has the potential to affect aircraft during critical phases of flight. Boeing, in Foreign Object Debris and Damage Prevention, estimate that FOD damage costs the aviation industry $4 billion per year.

All aerodromes are encouraged to have an active FOD management program in place. Aerodrome staff and pilots are reminded to keep an active lookout and retrieve any identified FOD before it becomes a hazard.

Further information about FOD management at aerodromes can be found on the Australian Airports Association website: Foreign object debris.

About this report

Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.

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1. Foreign object debris: Any object, live or not, located in an inappropriate location in the airport environment that has the capacity to injure airport or air carrier personnel and damage aircraft.
2. Back pressure: The application of back pressure to the yoke to slowly raise the aircraft’s nose and increase its angle of attack.

What happened

On 22 November 2018 a Cessna 210 was conducting a freight charter flight to Kilarney Station, Northern Territory (NT). The pilot was the sole occupant on board.

During approach to Kilarney Station, the landing gear failed to extend. The pilot attempted to extend the landing gear using emergency procedures with no success. The pilot then decided to conduct a return to Tindal Airport, NT and contacted the chief pilot and engineer in-flight. After unsuccessfully conducting troubleshooting procedures, it was decided the pilot would have to conduct a wheels up landing at a private airstrip with a grass runway area near Katherine, NT.

While the runway was prepared and emergency services were organised, the pilot entered a holding pattern to burn off fuel. At 1400 Central Standard Time, after multiple practice approaches, a wheels up landing was conducted on the grass strip resulting in a propeller strike and minor damage to the fuselage.

Engineering inspection

Following the incident, an inspection of the landing gear revealed that the hydraulic line connected to the nose wheel actuator had separated from its fitting. This subsequently resulted in a loss of hydraulic fluid in the gear down hydraulic line.

Figure 1: Damage sustained to aircraft after landing

Source: Operator

Figure 2: Broken hydraulic line from nose wheel actuator

Source: Operator

Safety message

Unanticipated failures can occur at any given time during flight. In this instance, the pilot took all appropriate actions by following non-normal procedures, communicating and coordinating with ground staff to conduct additional checks to assess the situation, and ensuring that he was well prepared for the wheels up landing resulting in a safe outcome.

This accident not only highlights the importance of comprehensive and periodic maintenance inspections, but also the importance of following emergency checklists and procedures and using every resource available to help resolve an issue.

About this report

Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.