Deliberately forced wing drop stalling in GFPT test
ATSB has published its report on the mid-air collision between a Cessna 152 and a Liberty Aerospace XL-2 near Bankstown on 18 December 2008. There was an astonishing time delay between the accident and the final report (two and a half years)
. The report stated the GFPT test required two demonstrations of the stalling sequence. Entry and recovery from a stall in the approach configuration, and entry and recovery from a stall with a wing drop. In addition, the investigation made mention of the CASA Flight Instructor Manual statement with reference to `advanced`stalling practice`, where the pilot must ensure the aircraft is recovered by at least 3000 feet agl. Presumably `advanced stalling` means stalling in a steep turn.
Two points come to mind. Modern training aircraft have benign stalling characteristics and there are stringent rules on the amount of wing drop permitted in the certification process. These aircraft include the Cessna and Piper singles of a previous era. Warbirds are different in this respect. Most current trainers waffle in a nose up attitude at the stall and are practically impossible to stall. Notwithstanding, the GFPT test requires recovery from a wing drop. However, to get these types to drop a wing requires deliberate gross mis-handling to attitudes never envisaged by the manufacturer of a non-aerobatic design. In fact, impossibly high nose attitudes and grossly exaggerated rudder inputs are needed in attempts to induce a wing drop. Even then a wing may not drop. That is how safe these aircraft are designed.
If we accept aircraft certification design that today's aircraft will not drop a wing at the point of stall, a risk of structural damage to airframe or engine is present if pilots are required to deliberately and grossly force the aircraft into exaggerated attitudes to achieve the outcome required by the GFPT.
Apply the same GFPT criteria to a Boeing 737 which has benign stalling characteristics and no pilot would remotely risk airframe damage by pulling up to 50 degrees nose high then push on full rudder to induce a wing drop. Not even in the simulator. Why then does such an antiquated and illogical requirement still exist in the GFPT test?
Deliberately forcing an aircraft into a manoeuvre beyond its design limitation is foolhardy and potentially dangerous. Whether conducted deliberately for practice or inadvertently, the aircraft should be grounded for a full structural inspection.
The second point is this. The original height limit of recovery by 3000 ft was for aerobatic manoeuvres and aimed at recovery from the looping plane or from a deliberate spin. Before first solo, students are required to demonstrate competency at recovering from a stall with minimum loss of height. Practice stalls in modern light aircraft should be easily recoverable by a competent student within 100 feet of height loss. This was even achievable in the old Tiger Moth days. Nowadays, with competency based training all the go, an instructor would not certify a student for solo stalling practice if height loss was excessive. It is therefore illogical to place 3000 ft as a minimum height at which all aircraft must be recovered from a practice stall. In any case, the time to climb above 3000 ft is expensive in terms of aircraft hire cost and utilization.
Stalling is not an aerobatic manoeuvre and the authors of the CASA Flight Instructor Manual, were living in the past when they mandated practice stalling as an aerobatic manoeuvre. On that basis a student should be certified competent in aerobatics before first solo.
CASA needs to take an enlightened attitude to light aircraft stalling characteristics and be realistic in terms of minimum height legislation.
Last edited by Tee Emm; 12th Jul 2011 at 13:57.