Nick Heard

Accident Analysis

With Nick Heard

Accident Analysis

Pitts pilot loses elevator control mid-flight

Losing control of one or more of the main controls sends shivers down the spines of many pilots. But, as Safety Editor Nick Heard reports, there are precautionary steps worth taking

Pitts G-BTOO
The Pitts aircraft that's the subject of this article. Photo: Graham C Evans

The pilot was conducting a test flight of a Pitts S-1C as part of the process for regaining the aircraft’s (G-BTOO) Permit to fly, following an extensive rebuild. Prior to take-off, the pilot stated that he had completed extended ground running of the engine and control checks to ensure all were operating normally. 

This was followed by an extended period for another 20 minutes of fast taxying to determine the handling characteristics he was likely to encounter on landing. After departure on Runway 03 at Popham, the pilot then conducted a series of flight manoeuvres for about 15 minutes, during which no handling issues were highlighted.

The pilot then joined in formation with another Pitts Special about 4nm from the airfield and began to route back. He stated that G-BTOO was trimmed in straight and level flight at 2,500 ft amsl with 140mph indicated airspeed.

At this point, he felt that he had some play on the stick in the pitch axis. He determined that he was able to move the control column fully forwards and backwards without any effect on the pitch attitude of the aircraft.

Concerned that the elevator may have detached completely, he asked the pilot of the other Pitts to undertake a visual check of the elevator, who, in turn, reported that it all looked normal.

The pilot then declared a Mayday on the Popham radio frequency stating that he had lost all elevator authority and was returning to the airfield. He assessed that the trim control had no tangible effect, and understood that the effects of the propeller would affect the pitch attitude of the aircraft when turning.

He commenced an unbalanced turn to the left and completed three to four turns, which allowed him to set up on the inbound heading for Runway 03. He then made a flat approach 1⁄2nm from the threshold at 140mph. The pilot assessed that the aircraft would touch down about a quarter of the way down the runway from the threshold.

As the aircraft passed over trees in the undershoot of Runway 03, the pilot reported that he felt the aircraft was affected by turbulence, which resulted in a steep nose down attitude of the aircraft. In response the pilot closed the throttle, before the aircraft struck the ground, flipped over, and came to a stop inverted.

The pilot sustained a severe laceration to the head and was taken to hospital.

The aircraft was initially examined in the hangar where it had been recovered, and it was stored inverted on a trailer. It was later transported to the AAIB facilities for a more detailed examination.

There were no access panels close to a bellcrank in the elevator control linkage, but it could be seen through a hole in the lower fuselage fabric, created during the accident. One of the push rods was no longer connected to the bellcrank which resulted in the loss of elevator control.

bell crank
One of the push rods was no longer connected to the bellcrank, resulting in the loss of elevator control. Photo: AAIB

Nick’s analysis

Of all the potential things that can go wrong in the air, the loss of one or more of the main controls is perhaps the most chilling. There have been some remarkable results from large aircraft that have suffered a total loss of hydraulic pressure, and hence normal aerodynamic control. 

The United Airlines DC10 accident in 1989 immediately springs to mind, in which the flight crew made an incredible landing when all hydraulics were lost after an uncontained engine failure. 

I also once had the privilege of flying with the First Officer of the A300 freighter that was hit by a surface-to-air-missile in 2003 on departure from Baghdad, again resulting in a complete loss of hydraulic pressure. His story of their successful landing is fascinating.

Before discussing the details of the Pitts event at Popham, and with all respect to engineers, in my experience several of the significant incidents in my flying career have occurred with aircraft fresh from some sort of heavy maintenance.

Mistakes happen in all areas of aviation, so I would always urge pilots to be particularly wary of aircraft just out of maintenance. Check and double-check as much of the aircraft as possible, and be particularly careful in checking controls – particularly that they are working in the correct sense. A former RAF colleague was killed in a Hawk after the ailerons were incorrectly reconnected after maintenance, leading to a loss of control immediately after take-off.

Turning to the Pitts accident, it looks like the pilot did a very good job in getting the aircraft onto the ground, such that at least his life was saved. A Pitts S1 is a brisk little aircraft that is not particularly easy to land even with full control. To do so without elevator control is particularly commendable.

The pilot explored the capability of the aircraft without the elevator control and took his time before attempting the landing. If I had been involved I might have considered diverting to an airfield with a longer into-wind runway rather than Popham’s 900 m grass strip, but there may well have been other reasons for not doing that.

A loss of one of the aircraft primary aerodynamic controls – aileron, elevator, or rudder – is very rare. Instances occur more often with aircraft that are rigged and derigged regularly, particularly gliders.

I have noticed very careful glider pilots who place signs up when they are rigging their aircraft asking not to be disturbed, as the distraction of a casual conversation can be a killer.

Traditional GA aircraft are more flyable after the loss of a control when compared to a Pitts S1. Recognising that you have the problem while in the air might be the first issue, perhaps the result of the loss of a control linkage due to vibration. 

Having recognised that there is a control problem, maintain control of the aircraft as best you can and take your time assessing the problem. There is no rush in landing the aircraft, assuming fuel is not a limiting issue.

Loss of rudder control is perhaps the least concern. Some pilots may not even realise that they have lost it! The only issue may be control on landing in any crosswind, so look for an into-wind runway.

Loss of aileron control is more problematic. However, don’t forget that the rudder will give you roll control as a secondary effect (remember that from PPL training?), but it would need a bit of practice while you have some height.

Loss of elevator control is the most serious. There may be a couple of options for you should this occur. Power adjustments will almost certainly offer some pitch control (power up – pitch up and vice versa). You may even be able to achieve some pitch control using the trim wheel, depending on the type of trim system.

In all cases don’t be afraid to get some ATC assistance, perhaps from D&D on 121.5. A diversion to an airfield with a long into-wind runway, fuel-permitting, will be preferable. Before attempting an approach try out the aircraft at a representative approach speed to see what the handling is like. Using flaps may not be such a good idea as they may induce difficult pitch changes that may be difficult to handle.

Perhaps try some of this out with an instructor sometime?

Some points to summarise:

  • If you appear to lose one of the flight controls, keep the aircraft under control at height and consider options. Take your time.
  • Get some help from ATC and try to find an airfield with a long into-wind runway.
  • Try out the aircraft at approach speed while still at height, avoiding using flaps if possible.
  • Practise this situation with an instructor on a convenient check flight.

AAIB report


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