The Partenavia unexplained accident at Essendon in 1978

[6317alan]

Part2 Sorry The Drawing is missing but would not transfer!




trim tab travel range number one 0 degrees + / – 1 degree Down To 16 degrees + / – 1 degree UP

This was the only range that was approved and certified in Australia for all P68B aircraft from the first of type certification on 23/1/75 until the mandatory modification incorporated in Partenavia Service Bulletin 41 in October 1978. This range is shown on the Trim Tab Travel Ranges drawing Page 118 coloured RED This travel range has an excess nose down trim capability of 18.5 degrees or 246 % excess capability. This travel range has an excess nose up trim capability of 10 degrees or 135 % excess capability. This excess capability has been calculated over that shown in Trim Tab Travel Range number 5 No design justification for this Trim Tab Travel Range has been discovered to A Baskett by the Department or Partenavia.

trim tab travel range number two 20 Degrees + / – 1 Degree Down - To 8 Degrees + / – 1degree Up

This range is shown on the Trim Tab Travel Ranges drawing as being coloured YELLOW.

This is the range that was approved and certified by the F.A.A Type Certificate Data Sheet A31EU Revision 3 dated 23/11/76. This range was not approved in Australia. This is the range that Partenavia claim was fitted to VH-PNW.



This appears to be the range fitted to VH-PNW as far as can be determined by wreckage reconstruction. This travel range has an excess nose down capability of 10.5 or 140% excess capability This excess capability has been calculated over that required in Trim tab travel range Number 5 No design justification for this trim tab travel range has been discovered to A Baskett by the Dept, or Partenavia

trim tab travel range number 3 20 Degrees +/- 1 degree To 4degrees +/- 1 degree Down

This range is shown on the Trim Tab Travel Range drawing as being coloured BLUE This is the range that was approved and certified by the R.A.I. Type Certificate Data Sheet SO/A151 Revision 5 dated 16/1/78 This Range was not approved in Australia This travel range has an excess nose down trim capability of 6.5 degrees or 86% excess capability This travel range has an excess nose up trim capability of 10 degrees or 135% excess capability. This excess capability has been calculated over that required in Trim tab travel range Number 5 No design justification for this trim travel range has been dis- covered to A Baskett by the Dept. or by Patenavia.

trim tab travel range number Four 1 degree Down To 15 degrees Down

This range is shown on the Trim Travel Range drawing as being



My Partenavia Report

coloured ORANGE This is the range that has been approved by the requirements to incorporate Partenavia Service Bulletin 41 in October 1978 This range is now approved in Australia This travel range has an excess nose down trim capability of 1.5 degrees or 22% excess capability. This travel range has an excess nose up capability of 5 degrees or 66% excess capability. This excess capability has been calculated over that required in trim tab travel range Number 5 No design justification for this trim travel range has been dis- covered to A Baskett by the Dept, or by Partenavia.

trim tab travel range number Five 2.5 degrees Down To 10 degrees Down This range is shown on the Trim Tab Travel Ranges drawing as being coloured GREEN This is the range discovered to A Baskett by the Dept. in C.A.A. document M-141-515-4 dated 17/2/89. This range is NOT approved in Australia. This travel range was established by flight test procedures to confirm compliance with F.A. R. 23-689(f) by a correctly rigged P68B aircraft at both forward and aft loading conditions, in so doing the total trim tab travel range required was also established for the Partenavia P68B (Note ) The method of determining the angular travel – was by dividing the 14degrees of travel of a correctly rigged aircraft by the number of divisions of travel indicated by the trim indica- tor i.e. 8.5 degrees. Therefore 1 division of trim indicator equals 1.65 degrees of trim tab travel. It is assumed linier along the trim indicator scale.




The M-131-515-4 document is the only document available that A Baskett has been able to discover that has any creditability to establish the actual trim tab travel requirement for the Partenavia P68B Aircraft.

Special Investigation Report 79-1

This Accident Investigation Report prepared by the Dept while appearing to be extensive and detailed in its investigation of this accident is in fact deficient in its pursuit of the subject matter to its logical extension of the ramifications of the total assessment of all the facts. The Dept have touched on the matter of pilot strength when they investigated control system failure caused by pilot input loads but chose to not detail in a similar manner the requirements of FAR 23-143(c) which limit the force required to be exerted by a pilot on a temporary basis not to exceed 75 pounds This report also omits to detail any reference to the fact that the position of the trim tab actuator was in a position that indicated that the trim tab travel was other than that certified in Australia This report omits to admit to the fact that the Dept failed to obtain flight test reports as required by ANO 101-22 prior to certi- fying the Autopilot/Electric Trim system. This report omits to detail that the Trim Tab Travel Range was excessive to that required to comply with FAR23-689(f) which establishes total trim capacity required for an aircraft. This report fails totally to address the fact that the Electric Trim System was never flight tested correctly as required. This report by not completely investigating all aspects of the Electric Trim System was able to minimize the design and certification deficiencies to enable the claim of pilot error to be raised by stating




“However, the more likely explanation is that the command trim switch was activated unknowingly.” This cannot be supported by any supported by any evidence as the coroner found at the inquest. The CAUSE as listed in this report is incorrect and misleading and would be more accurate if listed similar to the following.-

Cause The cause of the accident was that the aircraft became grossly out of trim at a height which did not permit time for the crew to affect recovery. The trim system design allowed control forces to be generated that exceeded pilot control force limits to be exceeded by a substantial amount. The manner in which the out of trim condition occurred has not been determined and the pos- sibility of a trim system malfunction cannot be eliminated.




All this was only achieved after many numerous legal orders were obtained as the Department did everything they could to stall and delay proceedings. I think their tactic was to maximize the delaying tactics hoping that I would tire of the whole process and just go away. I had to get a court order to get them to let me get copies All the documents were laid out on a conference table in a boardroom in no logical order. I then had to identify the relevant documents that I required to be copied. It ended up taking a full days work to sort out. In the end we ended up accepting an offer as I had been made aware that if I didn’t, Legal Aide would withdraw their support and I would be on my own from a financial point of view if I didn’t accept what was on offer. So reluctantly I accepted and at the end

[john_tullamarine]

FYI, the previous hyperlink now works.