Back to News list

Spar Web Survey Results

November 01, 2004

ABS has concluded its survey of members owning airplanes affected by the carry-through spar web ADs and MSBs. The data were evaluated during the independent engineering investigation which will be used in formulating ABS' response to possible changes in the airworthiness directives.

Thanks to everyone who took the time to research their airplane's history and respond to the survey.

ABS received 1007 responses, representing approximately 15% of the ABS members owning affected aircraft (~10% of the estimated remaining affected aircraft population). Results:

· 71 airplanes (7.1%) experienced some form of Mandatory Service Bulletin (MSB)-defined crack.

· 27 airframes (2.7% of those reporting) had cracks requiring installation of the doubler under the current Airworthiness Directives (ADs).

· 44 aircraft (4.4% of the reports) experienced cracking not meeting current AD criteria for doubler installation, but which would require the repair if the June 2004 MSB revisions become ADs and must now be repaired if operating under 14 CFR 135.

· Although a high number of reported cracks were in A36, Model 55 and Model 58 airplanes, cracks were also reported by owners of Model 33 Bonanzas, several V35Bs and other Model 35s as far back as S-models.

· There is no “smoking gun” or pattern of aircraft use that points to presence or absence of reported cracks.

Our best information is that, despite the limited response, the survey results present a representative picture of the affected fleet as a whole.

The survey information is just one of the data points used in ABS' independent engineering study.

*Responses indicating spar web cracks:*
		Under Current AD Rules			Of Survey Responses
Aircraft	Survey	Required	Cracked; Not	Total Reported	% Req.	% Cracked but	Total
Model	Responses	Patch	Req. Patch	With Cracks	Patch	Not Req. Patch	% cracked
S35	72	0	1	1	0.0%	1.4%	1.4%
V35	54	1	0	1	1.9%	0.0%	1.9%
V35B	108	1	4	5	0.9%	3.7%	4.6%
E33A	10	0	1	1	0.0%	10.0%	10.0%
F33A	80	0	1	1	0.0%	1.3%	1.3%
F33C	3	0	1	1	0.0%	33.3%	33.3%
36	22	1	4	5	4.5%	18.2%	22.7%
A36	130	9	6	15	6.9%	4.6%	11.5%
A36TC	9	1	1	2	11.1%	11.1%	22.2%
B36TC	12	0	1	1	0.0%	8.3%	8.3%
A55	9	2	0	2	22.2%	0.0%	22.2%
B55	93	6	12	18	6.5%	12.9%	19.4%
C55	13	3	1	4	23.1%	7.7%	30.8%
D55	6	0	1	1	0.0%	16.7%	16.7%
E55	15	0	2	2	0.0%	13.3%	13.3%
58	23	3	8	11	13.0%	34.8%	47.8%


Of 1007 total responses:
Totals	1007	27	44	71	2.7%	4.4%	7.1%
	Survey	Requires	Cracked; Not	Total Reported	% Req.	% Cracked but	Total
	Responses	Patch	Req. Patch	With Cracks	Patch	Not Req. Patch	% cracked
		Under Current AD Rules			Of Survey Responses

Back to News list

The American Bonanza Society

1922 Midfield Rd, Wichita, KS 67206

email or call at: (316) 945-1700