Part 1 - Airworthiness Articles

AAC 1-62

Bellanca (Champion) Wing Spars

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The wing structure of the Bellanca (Champion) series of aircraft has been the subject of a number of Airworthiness Directives:

	AD/CHA/12 Wing Ribs - cracks and/or buckling of the rib flanges
	AD/CHA/21 Wing Rib/Spar Attachment and LE Support Block Nails - loose and missing nails
	AD/CHA/23 Wing Spar Compression Failures
	AD/CHA/23 was raised in response to FAA AD 87-18-09 and to known failures of Bellanca Scout wing spars which had resulted in fatal accidents. This required cutting access holes in the fabric and visually inspecting the side of the spars.

However, due to further incidents and accidents, many aircraft have had the wing spars inspected thoroughly for compression damage and considerable damage was found in some cases. An alarming aspect is that most compression shakes found were underneath rib flanges, in line with the nail holes, and often associated with indentations in the spar edge caused by movement of the ribs. Also, the locations of the shakes were more widespread than in the area of the lift strut attachments. Thus, these may not be readily found by the inspection detailed in the AD.

Also noteworthy was the fact that what was often perceived as a minor superficial wingtip groundstrike caused extensive internal damage to the spars!

Following a fatal accident in Queensland, BASI have been conducting a thorough investigation of that aircraft and another Scout which was found to have a number of compression failures in the spars. Also investigated was a spar from a Decathlon, which while condemned for another reason, contained a compression shake.

The Scout model has a longer wing-span than the Citabria or the Decathlon, with longer wing overhang past the lift strut attachment, and higher gross weight. This may explain why the compression failures have been biased towards the Scout model. Also the Scout is not approved for aerobatics, so excessively violent manoeuvres, turbulence or unauthorised aerobatics could easily result in catastrophic wing failure, particularly if negative load factor is applied, and spar damage is present.

The FAA is considering revising the AD.

Meanwhile, in view of the above comments, owners of these aircraft are strongly advised to fully inspect the wing spars in compliance with AD/CHA/23 in much more detail than that formally required by the AD.

Whilst the Scout is probably more susceptible to the spar damage, all models can be affected. The AD is currently applicable to Scout aircraft, but owners of other models should consider fully inspecting the spars if there is any possibility that the aircraft has suffered what may only seem a mild wingstrike, or has ground looped and wing tip damage has occurred or the aircraft has overturned.