Sequence of events
The Cessna Silver Eagle aircraft, a turbine-powered, pressurised Cessna 210, was conducting a private flight from Maroochydore to Bankstown under the Instrument Flight Rules (IFR), cruising at flight level (FL) 160. Meteorological conditions conducive to icing had been forecast for the route.
While enroute, the pilot faced adverse weather and requested a diversion around the weather. Air traffic control (ATC) cleared the aircraft to divert then, when clear, to track direct to Mount Sandon. The pilot requested, and was approved to, climb to FL 180. Twenty four minutes later, the pilot told ATC that he required a descent to FL 140 due to icing. Six minutes after that, the pilot stated that he required a further descent to FL120 due to icing, and four minutes later, requested descent to 10,000 ft due to icing.
Two minutes later, the pilot reported an engine failure. One minute and 43 seconds later he reported that he had lost generator power and that the aircraft was descending through 8,500 ft. ATC then asked the pilot to activate the emergency locator transmitter (ELT). A Distress Phase was declared and, after further attempts to communicate with the pilot were unsuccessful, search and rescue (SAR) action was started.
Several hours later, search aircraft found the wreckage on steep mountainous terrain, 380 m south-east of its last position showed by radar. The accident was not survivable.
Onsite investigation revealed that the right wing had failed before impact, both at midspan and at the fuselage attachment point, because of aerodynamic forces that exceeded the wing structural load limits. The empennage had also separated from the fuselage before impact. The right horizontal stabiliser and elevator were not present at the accident site. Objects thought to be parts of the missing empennage were sighted from the air. Their location was 330 m from the main wreckage site, and on the northern slope of a ridge. The main wreckage was on the southern slope. The wreckage trail was consistent with the direction of flight as recorded on radar.
The fuselage, with the engine and left-wing still attached, had impacted the ground in a steep nose-down, inverted attitude. The cabin section of the fuselage comprising the pressure hull, had remained intact until impact with the terrain. The landing gear and wing flaps were found to be in the retracted position.
The evidence showed that the propeller was still attached to, and was being driven by, the engine at impact. The engine and cockpit firewall, with most of the instrument panel attached, had separated from the fuselage during the impact sequence and had been destroyed by post-impact fire. Most of the left-wing was also destroyed by post-impact fire. The intensity of the fire suggested the aircraft was carrying a significant fuel load at impact. There was no evidence of any pre-impact fire.
The aircraft had been fitted with a fixed and two portable ELTs, all of which had been destroyed by impact forces.
The engine was subsequently stripped and inspected. The inspection revealed that the engine was producing significant power at impact. The wreckage examination did not reveal any pre-existing technical fault that would have contributed to the accident.
The aircraft was registered in the USA and was maintained to US
Federal Aviation Administration requirements. It was fitted with an
Allison 250-B17F/2 turbo-propeller engine. Section 2 page 5 of the
approved flight manual supplement for the aircraft stated:
"For flight at ambient temperatures of 4 degrees Celsius and below, the fuel used in this aircraft MUST have an anti-icing additive in compliance with MIL-I-27686D or E or Phillips PF A55MB, incorporated or added into the fuel during refuelling in accordance with the additive manufacturer's instructions."
Section 2 page 9 of the approved flight manual supplement for
the aircraft stated:
"Flight into known icing conditions is prohibited."
The engine-driven generator installed in this aircraft was designed to automatically shed all electrical load when engine compressor revolutions per minute (RPM) fall to 70%.
Inspection of the aircraft technical logbooks revealed compliance with all applicable Airworthiness Directives and Service Bulletins.
The aircraft was refuelled before departure from Maroochydore. No evidence was found to suggest that anti-icing additive had been added to the fuel at that time.
On the day of the accident, several other aircraft, including one high-capacity regular public transport aircraft, had been refuelled from the same fuel supply as N62J. None of the pilots of these aircraft reported any problems with fuel.
The pilot held a US commercial pilot certificate with a valid Class 2 medical certificate, a command instrument rating, and was endorsed for the aircraft type. His total experience was 3,229 hours with 629 hours on the aircraft type. He was reported as being a cautious pilot who planned his flights carefully and correctly applied inflight procedures. He was aware of the aircraft limitations about flight in icing conditions.
Pathological and toxicological examination did not reveal any evidence of any medical condition affecting the pilot that could have prevented him from safely operating the aircraft.
The amended area forecast showed rain and thunderstorms with a freezing level of 10,000 ft; moderate icing in the tops of large cumulus, altocumulus and altostratus cloud, temperatures of 2 degrees C at 10,000 ft and minus 6 degrees C at FL 140.
The actual freezing level was approximately 11,500 ft with severe icing and turbulence in thunderstorms. Conditions in the area at the time the pilot reported the engine failure were conducive to airframe and engine intake icing. Interpretation of the enroute weather reports suggested that the aircraft might have passed through a line of showers and thunderstorms.
Although it cannot be confirmed, it is likely the engine RPM reduced significantly because the aircraft was operating in conditions for which it was not designed or certified. The apparent generator failure is consistent with a drop in RPM. As the aircraft descended into warmer air below the freezing level, with enough fuel and the ignition system working, the engine probably returned to normal operation.
The inflight breakup of the airframe resulted from the airframe being stressed beyond its design limit. Whether this stress resulted from loss of control by the pilot or an encounter with severe turbulence or an attempt by the pilot to avoid terrain could not be established.
|Date:||27 October 1999||Investigation status:||Completed|
|Time:||1245 hours EST|
|Location:||14 km W Hernani|
|State:||New South Wales||Occurrence type:||In-flight break-up|
|Release date:||11 July 2001||Occurrence category:||Accident|
|Report status:||Final||Highest injury level:||Fatal|
|Aircraft manufacturer||Cessna Aircraft Company|
|Type of operation||Private|
|Damage to aircraft||Destroyed|
|Departure point||Maroochydore, QLD|
|Departure time||0834 EST|
|Role||Class of licence||Hours on type||Hours total|