Gremline Flight Safety Report: Recent Incidents & Timely Reminders

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the gremline digest — recent incidents & timely reminders

Recent Incidents & Blasts from the Past

Your editors decided to escape from wet and windy Wales in August but we are back in harness and have back-filled the August slot with six brief articles. The first two are based on very recent incidents, the remaining four, though less recent, still carry salutary lessons.


Stow It!
A recent accident to a light aircraft occurred because the control stick became jammed by the pilot’s kneeboard mounted on his thigh. The pilot pulled back hard to free the restriction, then the stick moved rapidly to apply full up elevator. The aircraft stalled into the ground causing considerable damage to the airframe, engine and propeller.
A CAA General Aviation Safety Information Leaflet (GASIL) issued in September 2003 recommends that while kneeboards are useful during cruise they should be placed in a safe, secure place during critical phases of flight such as takeoff and landing.
Now you know why.

 

How Long May You Leave Your Parked Aircraft?
Many GA aircraft are either parked on the airfield or stored in a hangar for several weeks without use, particularly during winter months. Did you know that CAP 411, the Light Aircraft Maintenance Schedule (LAMS) or its replacement CAP 766, the Light Aircraft Maintenance Programme (LAMP) specify a MAXIMUM period between engine runs? Both documents require piston engines to be either run EVERY 14 DAYS or turned over by hand EVERY 7 DAYS.
I suspect that this regulation is not observed by all GA aircraft owners. Does it matter? Well, yes it does. A recent fatal accident involving a PA23 Aztec when both engines produced only reduced power and the pilot spun off an attempted turn back after takeoff was probably caused by failure to observe the above requirement. The aircraft had spent long periods stored in the open over the previous 5 years. The fuel systems of both engines were corroded causing restricted flow through the injectors. The injectors had required cleaning prior to the fatal accident flight and both engines appeared to run satisfactorily on the ground. However, after takeoff both engines produced visible smoke and the aircraft seemed to have a much reduced rate of climb. It climbed slowly at low speed, producing smoke from both engines. The aircraft turned steeply towards the runway reciprocal, the left wing dropped suddenly and the aircraft pitched down, hit the ground and burst into flames.
Ignoring the errors in technique by the pilot after suffering incipient engine failure, the root cause of this accident was the problem with the engines.
I have been flying for over 55 years but was not aware of the REQUIREMENT to either run the engine every 14 days or to turn it by hand every 7 days until I read about it in a recent issue of the CAA General Aviation Safety Information Leaflet (GASIL). Does everyone else know about this requirement? Does everyone observe it? How about your Gliding Club tug aircraft? Who takes care of the Group aircraft? Have you ever left your aircraft unattended for more than 14 days?

 

 

Lost Electrics

A Beechcraft F33 Bonanza with two pilots on board was flying from Blackbushe Airport to Bournemouth and was in contact with Farnborough Radar when the aircraft had a total electrical failure.

The aircraft turned right onto a northerly heading to avoid controlled airspace and the systems were checked. Blackbushe was contacted by mobile phone and advised that the pilot intended to continue north to Wellesbourne Mountford, an airport with which he was familiar. The weather deteriorated in rain and visibility below VFR limits. Abingdon Airport was visually identified and Farnborough ATC was contacted by mobile phone to advise them of the intention to land there. The landing gear was lowered manually but, being unable to check that the gear was fully down, the pilot decided to perform an engine off landing. The engine was shut down and the fuel selected off over the runway threshold. The aircraft landed very gently but the gear collapsed while the aircraft came to rest on the runway centreline. There was no fuel spillage and no injury to the occupants.
The engineering organisation that recovered the aircraft from Abingdon reported that the aircraft’s electrical system, normal electrical landing gear system and manual gear extension system all operated normally prior to aircraft recovery so no technical reason for this accident was found.


The value of carrying a mobile phone in the air with a Flight Guide listing airfields, facilities and their telephone numbers was proved in this case.

 

This report is closely based on AAIB Report ew/G2004/10/08, which source is gratefully acknowledged.

 

 

Don’t Assume — Check!

How often during training are we reminded that ‘Vital Actions’ are VITAL?

An experienced professional pilot flew his Piper PA-34 Seneca II to Stapleford airfield early in the morning to have the autopilot repaired. The repair was completed and the engineers told the pilot that only the autopilot computer had been removed to complete the repair. The pilot lined up for departure on Runway 22 which is asphalt for the first 600 metres and grass for the remaining 477 metres. There was a 15 kt crosswind from the right. The pilot found he was ‘fighting to keep the nose up’ as the aircraft left the ground. He tried to use the electric elevator trim but found it did not work. He abandoned the takeoff and landed heavily on the remaining grass runway. The left propeller touched the ground before the aircraft was brought to a halt.
Examination showed the elevator trim in the fully nose-down position and that the circuit breaker for the electric trim had been pulled. The pilot candidly admitted that he had not checked the trim prior to departure because he assumed it had been undisturbed during the repair to the autopilot. He accepts he should have checked the trim and believes the engineers should have pointed out that the circuit breaker had been pulled and they should have returned the elevator trim to the take-off position when they completed the autopilot repair.
Checks and vital actions by the pilot are fundamental to the safe operation of an aircraft. There can be no justification for taking short cuts or making assumptions. This accident also highlights the importance of accurately documenting all work that has been done on an aircraft, especially when it has implications for operational safety.
(Based on AAIB Report EW/G2004/08/13 which source is gratefully acknowledged).

 

 

Hours Alone Are Not Enough #1

Over the years there have been a number of accidents and incidents involving GA aircraft where the pilot has held a professional licence and has thousands of hours on ‘heavy metal’ but few (recent) hours on light aircraft.

A pilot holding an ATPL with 7,500 hours experience but with only 10 hours on type was travelling at low speed after landing his Pitts S-1C aerobatic biplane in benign weather when the aircraft suddenly ground-looped violently to the right. The lower left wing and the propeller struck the ground and the aircraft pitched rapidly over its nose before coming to rest inverted. The pilot was able to climb out of the wreckage uninjured. His five-point harness and crash helmet protected him from injury.
The Pitts is a short-coupled aircraft that demands constant and immediate control input while taxiing in any condition. It is all too easy to relax at the end of a landing run. Student pilots on Harvards in the 1950s were given some very good advice that may be applied to any aircraft.
“Remember, the landing is not complete until the wheels have stopped turning.”

 


Hours Alone Are Not Enough #2

Another pilot holding an ATPL with over 4,000 hours experience but with only 10 hours on type was taking off from a grass strip in his Boeing A75N1 Stearman biplane powered by a 220hp Continental radial engine. The air temperature was +10C above standard and the aircraft was about 200 lb below its maximum authorised take-off weight. The aircraft left the ground in a ‘three-point’ attitude and did not accelerate. The Stearman reached a maximum altitude of about 100 feet agl during this attempted takeoff. Witnesses recalled the aircraft appearing to be flying close to the stall, with a series of wing drops before it descended into a field beyond the airfield boundary with the engine apparently producing full power until impact. The aircraft suffered severe damage on impact and caught fire after turning over onto its back. The pilot and passenger were able to escape without assistance, although the pilot was injured.

The following comments are those of the Gremline editor and do not profess to reflect the views of AAIB.
My own experience on this version of the Stearman is limited to a few hours on the PT17A, with most of my time on the much more powerful version with the 450 hp Pratt & Whitney R985 engine.
This pilot had very limited experience on the Stearman. From the evidence provided by four witnesses, including at least one experienced pilot, it appears that the aircraft left the ground in a nose high attitude, did not accelerate and appeared to climb to about 100 feet agl while remaining close to stalling speed before descending to impact. In my opinion, this is a classic description of an aircraft of limited performance climbing out of ground effect whereupon the large increase in lift induced drag overcame the small margin of excess power available and caused the aircraft to stall and descend into the ground. Had the aircraft achieved a lower nose attitude (higher tail attitude) before leaving the ground it is more likely that it would have accelerated to a speed sufficient to allow it to climb away in safety. Had the pilot lowered the nose as far as possible once he recognised the lack of acceleration then it is possible that the Stearman would have accelerated sufficiently to climb away. This opinion is not meant to be a criticism of the pilot who lacked experience on type, but is intended to bring to the attention of all pilots the relationship between ground effect and lift induced drag, and particularly to those pilots who operate light aircraft with limited excess performance from runways of limited length.
There is a full explanation of the relationship between lift induced drag and ground effect in our October 2007 article
Accidents on Takeoff.
(Based on AAIB Reports EW/G2004/07/08 and EW/G2004/08/01 which sources are gratefully acknowledged).

 

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