The bulletin
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FAA Aircraft Certification Service
SPECIAL AIRWORTHINESS
INFORMATION BULLETIN SUBJ: Volkswagen Engine Cylinder Head Fastener Torque SAIB: CE-07-43 Date: September 4, 2007 This is information only. Recommendations aren’t mandatory.
Introduction
This Special Airworthiness Information Bulletin alerts the operators of airplanes powered by Volkswagen air-cooled engines of an airworthiness concern where the engine loses power due to the loss of cylinder head fastener torque.
Background
On March 5, 2006, at 1430 Central Standard Time, an experimental amateur-built Quickie Q-2, N89WW impacted an agricultural field near Edwardsville, Illinois, receiving substantial damage .
After takeoff from St. Louis Regional Airport (ALN), Alton/St. Louis, Illinois, the pilot reported to air traffic control that the airplane was having engine problems. Visual meteorological conditions prevailed at the time of the accident. The flight was operating under 14 CFR Part 91. The pilot was fatally injured.
A post-accident investigation revealed that both left cylinders had no compression. All the cylinder head fasteners were found with zero torque. In fact, the lower forward hold down fastener was backed out 1/8 inch. After removing the cylinder head and barrels for both left cylinders, both barrels and both heads showed evidence of severe combustion gas blow by . Metal was melted out of the heads at the bottom forward and bottom aft hold down fastener areas, obviously caused by the combustion gas blow by.
2 Recommendations
Ensure that you, as the owner/operator, follow the engine manufacturer/supplier cylinder head torque procedures (initial and repetitive).
The following are the recommended torques for the cylinder head fasteners on Volkswagen Type I, Type II, and Type IV engines:
Type I engine with 10mm head studs 23 ft-lbf Type I engine with 8mm head studs 18 ft-lbf Type II engine 23 ft-lbf Type IV engine 23 ft-lbf
NOTE: The above torques are offered only as information. Refer to the engine manufacturer/supplier maintenance instructions for the recommended cylinder head torque procedures.
The following is a summary list, but not a complete list, of Volkswagen based aircraft engine manufacturers/suppliers:
AeroConversions, Inc.
P.O. Box 2521 Oshkosh, WI 54903-2521
(920) 231-8297
Great Plains Aircraft Supply Co., Inc.
P.O. Box 222 Bennington, NE 68007 402-493-6507
Revmaster Aviation 7146 Santa Fe Avenue East Hesperia, CA, 92345 760-244-3074
For Further Information Contact
Peter L. Rouse, Aerospace Engineer, Small Airplane Directorate; phone: (816) 329 4135; email:
peter.rouse@faa.gov