Regulatory Brief -- Raytheon (Beech) Carry-Through Spar Cracks

Regulatory Brief

Raytheon (Beech) Carry-Through Spar Cracks

The issue:

On June 2, 2004, Raytheon Aircraft Corporation (RAC) released revisions to Mandatory Service Bulletins 53-2360 and 53-2269, which may lead to changes in Airworthiness Directives (ADs) 90-08-14 and 95-04-03. These service bulletins call for the inspection and repair as necessary of cracks found in the wing carry-through spar webs of many models of Beech Debonair, Bonanza, Travel Air, and Baron aircraft. These revisions remove the allowable crack limits that were permitted in prior releases and call for repairs to any identifiable cracks.

Revisions to these bulletins have the potential to affect all owners of Bonanza, Debonair, Travel Air, and normally aspirated Baron aircraft produced between 1957 and mid-1985 (Baron), mid-1986 (Bonanzas except B36TC) and mid-1987 (B36TC). These revisions stem from a change in FAA policy to no longer allow aircraft operations with known cracks.

The change in FAA policy regarding known cracks is a subset of the larger issue of aging aircraft. With the average age of a general aviation aircraft well past 30 years and many well over 40 years, the FAA is taking a close look at their continued airworthiness. While not directly related, the recent and very public wing failures of a firefighting C-130 and PB4Y aircraft, as well as two T-34 wing failure incidents, have drawn much attention to the continued operation of aging aircraft. Although these are vastly different situations, they contribute greatly to the FAA's emerging "no cracks" philosophy and aging aircraft policy.

The importance to our members:

These service bulletins and the potential of new airworthiness directives replacing two existing Ads, 90-8-14 and 95-04-03, will impact thousands of aircraft. Existing ADs require the repetitive inspections of the carry-through spars of affected aircraft and allow for the continued flight in many instances of aircraft with cracks. Stop-drilling and continued inspections with shorter intervals are currently authorized for cracks in certain locations and within specific parameters outlined in the ADs. Cracks beyond specified tolerances and multiple cracks in certain locations require the installation of a spar reinforcement kit. Many aircraft have continued to fly after cracks have been detected with either stop drilling or continued inspection without incident.

If the FAA revises ADs 90-08-14 and 95-04-03 to reflect the changes in the service bulletins as is anticipated, existing spar cracks that were allowed under the current ADs may require the installation of a spar repair kit. Aircraft that have continued to be operated for many years and many hours with known cracks under continued inspection will no longer be allowed to do so.

To date, most airplanes needing spar crack repair have been Barons and Model 36 Bonanzas, although some Model 33s and V-tails as early as P35 have also been found in need of repair under the current AD.

Most Recent Web Posting:

AOPA, American Bonanza Society seek solution to spar web cracking problem
Aircraft owner input requested

AOPA and the American Bonanza Society (ABS) continue to research and evaluate the issues associated with Beechcraft Bonanza-Baron spar web cracking. Determining the real safety issues and finding the best resolution are the top priorities. And you, the aircraft owner, are a vital link in supplying the information needed to find that solution.

ABS has released a second survey for aircraft owners who are affected by this issue - owners of Bonanzas, Debonairs, Travel Airs, and normally aspirated Barons built between 1957 and the late 1980s. The scope of this survey has been narrowed to give the society precisely the information it needs, and it will be used to supplement data gathered from the previous one.

"The ABS needs a high response rate from the affected aircraft owners so that they can pull reliable conclusions from the results," said Rob Hackman, AOPA manager of regulatory and certification policy.

ABS has gathered data with a detailed survey of owners and from the aerospace structures engineers hired to find the cause of the cracks in the carry-through structure, bulkhead flanges, and fuselage skins. However, more information is needed.

ABS is asking all of the affected aircraft owners to complete and send them a printed copy of the survey along with a photograph or sketch of the cracks before January 31.

Surveys can be mailed or sent via fax:

ABS Manager of Technical Services
1922 Midfield Road
Wichita, KS 67209
Fax: 316/945-1710

Affected Aircraft:

Mandatory Service Bulletin 53-2269 Rev. 2 and AD 90-08-14 Rev. 1:

  • Travel Air 95, B95, B95A, D95A, and E95 serial numbers TD-1 through TD-721.
  • Baron 95-55, 95-A55, 95-B55, and 95-B55A serial numbers TC-1 through TC-349 and TC-351 through TC-2456.
  • Baron 95-C55, 95-C55A, D55, D55A, E55, and E55A serial numbers TC-350 and TE-1 through TE-1201.
  • Baron 95-B55B (T-42A) serial numbers TF-1 through TF-70.
  • Baron 56TC and A56TC serial numbers TG-1 through TG-94.
  • Baron 58 and 58A serial numbers TH-1 through TH-1475.

Mandatory Service Bulletin 53-2360 Rev. 1 and AD 95-04-03:

  • Debonair/Bonanza 35-33, 35-A33, 35-B33, 35-C33, E33, F33, and G33 serial numbers CD-1 through CD-1304.
  • Debonair/Bonanza 35-C33A, E33A, and F33A serial numbers CE-1 through CE-1192.
  • Bonanza E33C and F33C serial numbers CJ-1 through CJ-179
  • Bonanza H35, J35, K35, M35, N35, P35, S35, V35, V35A, and V35B serial numbers D-4866 through D-10403.
  • Bonanza 36 and A36 serial numbers E-1 through E-2397.
  • Bonanza A36TC and B36TC serial numbers EA-1 through EA-471.

Pre-H35 Bonanzas; 58TCs and 58Ps; and A36s, F33As, B36TCs, and 58s built since mid-1985 (Baron), mid-1986 (Bonanzas except B36TC) and mid-1987 (B36TC) are NOT affected by this issue.

Significant provisions:

RAC Mandatory Service Bulletin 53-2269, Rev. 2 and 53-2360, Rev 1

  • Inspect wing forward spar carry-through structure forward and aft frames for cracks within the first 1,500 flight hours.
  • If no cracks found, inspection is to be accomplished at recurring 500 flight-hour intervals.
  • If cracks are found, the applicable spar repair kit must be installed.
  • Aircraft with known cracks in compliance with prior service bulletins and ADs must install the applicable spar repair kit.
  • Compliance times for installation of the appropriate kits vary depending on length and location of cracks and are specified in the service bulletin.
  • Estimated man-hours required to complete the anticipated repair run from 60 to 90 hours.

AOPA position:

AOPA is concerned with the FAA's change in policy regarding known cracks and its impact on the general aviation fleet. Additionally, we are seeing the overall effects of the FAA's concern regarding aging aircraft on numerous makes and models of aircraft. Aging aircraft and their continued operation is an issue that each owner should become familiar with. Understanding the issues as they relate to each aircraft will help all involved in determining legitimate safety concerns and developing cost-effective methods for addressing them. AOPA is working closely with the various type clubs familiar with the specific makes and models impacted to determine the best course of action to address the FAA's concerns as they relate to each aircraft type.

For this issue, AOPA is working closely with the American Bonanza Society (ABS), which is regarded as the authority on Beech aircraft. Two highly experienced and licensed aerospace structures engineers have been engaged to further research this issue. The criteria for selection included aircraft structures expertise, professional experience, and professional credentials.

The engineers have begun their in-depth work, which was preceded by initial opinions that they believe a better understanding is needed of the cracking mechanism in the carry-through structure as well as the bulkhead flanges and fuselage skins. They are both concerned that the ultimate recommended fix properly addresses all the potential safety implications and that "the cure is not worse than the problem." They also share ABS' and AOPA's concern that spar repair kits be properly installed and extreme care taken if huck bolts need to be removed and reinstalled in the field.

ABS recently learned that RAC has sold over 2,000 repair kits to date. This number far exceeds earlier estimates of the extent of spar web cracking but provides an opportunity to develop a database on cracking information that will greatly help our engineers evaluate the problem. A questionnaire on this subject has been posted on the ABS Web site News and under the General Maintenance topic on ABS' Hangar Flying bulletin board, and ABS is collecting responses for the engineers' use.

Further, ABS is speaking with Raytheon Aircraft about repair kit pricing and availability and is encouraging the company to ramp up production of kits if they have not already should a larger number of owners need kits for compliance.

UPDATE:

  • ABS has concluded its survey of members owning airplanes affected by the carry-through spar web ADs and MSBs. Results are posted on the ABS Web site.
  • ABS and AOPA have received the engineering reports in the spar carry-through investigation. We have reviewed these reports in a four-hour meeting between ABS and AOPA management on November 4.
  • ABS has submitted the spar web engineering reports to the FAA's Aircraft Certification Office in Wichita, along with a position paper stating ABS' requests for further action. The reports were concurrently given to Raytheon Aircraft's engineering department for its review.
  • ABS has released a Request for Proposals for a Finite Element Analysis engineering study of the Beech carry-through structure. The RFP is posted on ABS's home page.

UPDATE:

  • ABS has released a second survey for aircraft owners who are affected by this issue - owners of Bonanzas, Debonairs, Travel Airs, and normally aspirated Barons built between 1957 and the late 1980s. The scope of this survey has been narrowed to give the society precisely the information it needs, and it will be used to supplement data gathered from the previous one.

Related documents:


Updated Tuesday, January 18, 2005 7:14:05 PM