C of G position- the invisible killer


c140a

A Piper Cherokee 140

We have recently been discussing Mass & Balance (still called weight and balance in the States but now refered to as mass in the UK) in regard to this accident which sadly killed this Walsall pilot and his two passengers.

Fatal accident- G-APWS Piper Cherokee 140 – near Little Haywood, Staffordshire

It would seem that his party piece was to show passengers a stall turn at low level but on this occasion with a more rearward C of G, caused by an additional passenger, the aircraft’s handling characteristics may well have changed to an extent which completely surprised the pilot resulting in the aircraft hitting the ground at very high speed.

In addition to the manoeuvre the accident highlighted the pilots cavalier and illegal approach to personal licensing, aircraft maintenance and the keeping of engine and airframe logbooks. As I always tell you:

IF YOU PERSISTENTLY BREAK THE RULES THE AIRCRAFT WILL EVENTUALLY BREAK YOU!

Once you move from a two seat training aircraft to a 4 or 6 place aircraft it’s essential you understand how to calculate C of G and fully understand Normal & Utility category mass & balance restrictions.

CAA Safety Sense Leaflet – Mass & Balance

FAA Weight & Balance

Before completing any aerobatic manoeuvre always make a airborne HASELL check, and that includes a planned steep turn in excess of 45 degrees.(some instructors disagree with this HASELL check but I would rather over teach safety then just blindly repeat folk lore). The A & S of the HASELL check should prompt you to consider the C of G position. Ive known a pilots throw an aircraft into a low level steep turn over a friend’s house and totally forget they were carrying rear seat passengers!

A = airfame and S = security from the standard HASELL check
In relation to C of G, A – airframe should trigger the question, what category am I in, Normal or Utility?
In relation to C of G, S – security should trigger the question, are there any loose articles that could change the C of G if I undertake an aerobatic manoeuvre

Miles Baddeley took off from Shobdon one evening with 3 passengers in the club Piper Cherokee 180. Sitting next to him was the gliding club tug pilot, who specialised in showing off. During the flight the tug pilot decided to show everyone a spin! Unfortunately when he came to show the recovery he had a problem, it wouldn’t recover. They tried everything as they hurtled towards the ground but it would not come out. In a last attempt before they hit the ground Graham Ticton, an instructor at the school, lent forward to try to jockey the throttle backwards and forwards. It is believed that this movement of his body weight actually affected the recovery (C of G) and the spin stopped but by now the aircraft was just about to hit the ground. Using a massive stabilator input they managed to pull out of the dive and just miss the ground, however the input was so severe that both wings were wrinkled and damaged beyond repair. They all ended up in the magistrates court at Leominster!

I had spun that aircraft many times in the normal category (pilot & 1 pax) and like most Cherokees it was docile, in fact you had to hold it in to keep it spinning. With a rearward C of G out of normal limits however you are a test pilot and if you are unlucky a dead test pilot.

Why is it by the way that a lot of flying schools do not have weighing scales,  yet another example of low standards?

Fly safe and remember, you cannot see C of G, you have to calculate it!

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2 thoughts on “C of G position- the invisible killer

  1. The A&S, it spoils the flow of a good read if having to stop to check an acronym or abbreviation. I haven’t found this one yet (A&S)! RTFQ, there are no dumb questions etc! Keep up the good work, Mike D

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    • Thank you for your comments
      Sorry, I thought that was obvious, a mistake instructors often make! I will edit the article

      A = airfame and S = security from the standard HASELL check
      In relation to C of G, A – airframe should trigger the question, what category am I in, Normal or Utility?
      In relation to C of G, S – security should trigger the question, are there any loose articles that could change the C of G if I undertake an aerobatic manoeuvre

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