Regulatory Brief -- T-34 wing spar issue

Regulatory Brief

T-34 wing spar issue

The issue:

In April 1999, a Beech T-34 engaged in mock aerial combat crashed near Rydal, Georgia. NTSB reports indicate that the crash was preceded by an in-flight separation of the wing. Metallurgical examination revealed fatigue cracks at multiple locations in the wings of the accident aircraft. As an interim fix to this problem, the FAA issued an AD placing airspeed and G-load limitations on the T-34. Raytheon developed a "mandatory" service bulletin (SB) 57-3329 to inspect the critical fatigue locations on T-34 aircraft. On May 5, 2000, the FAA published a proposed AD (2000-CE-09-AD) mandating Raytheon's recommended wing spar inspections. On July 2, 2001, the FAA finalized the AD mandating wing spar inspections. On July 30, 2002, the FAA issued a Special Airworthiness Information Bulletin listing approved AMOCs and extending the AD compliance deadline.

On November 19, 2003, near Montgomery, Texas, a second T-34 Mentor experienced a separation of the right wing and crashed, causing two fatalities. Preliminary investigation of the accident determined that AD 2001-13-18, T-34 Wing Spar Inspection, was not accomplished. A group that provides mock aerial combat and upset training operated this aircraft, like the aircraft mentioned above. This was the second such crash of a T-34 aircraft used in this type of aerial activity. On December 22, 2003, the FAA issued an Airworthiness Concern Sheet (ACS) as part of the Airworthiness Concern Process. In the ACS, the FAA stated that it was considering rescinding all four AMOCs to AD 2001-13-18 and the 200-hour extension that was referenced in SAIB CE-02-38R2. The reason for rescinding all four AMOCs given was because they did not address Location (3) and/or Location (4). The reason for rescinding the 200-hour extension given was that it was based on engineering judgment that the lower rear bathtub fitting was a precursor to fatigue cracking in the wing. The FAA no longer felt the lower rear bathtub fitting was a precursor to fatigue cracking in the wing based on the data from the accident in Texas.

The FAA published a revision of AD 2001-13-18 on March 1, 2004. This AD rescinded all four approved alternate methods of compliance (AMOCs) and required all T-34s that had accumulated 80 hours time in service since the original AD was issued in August 2001 to comply with Raytheon Service Bulletin SB57-3329 for additional inspections. These inspections would continue at 80-hour intervals.

December 10, 2004 - The Federal Aviation Administration has issued an emergency AD applicable to all T-34 aircraft models following the December 7, 2004, in-flight separation of the left wing of a third aircraft.

March 7, 2005, the FAA issued Special Airworthiness Information Bulletin (SAIB) CE-05-36 to alert T-34 owners of an approved inspection program for airplanes that have not yet reached 3,800 hours total time in service (TIS).

UPDATE: April 19, 2005, the FAA has issued several "alternate means of compliance" (AMOC) that will allow most T-34s to get back in the air this summer. The new AMOCs will allow most owners to fly their T-34s for up to 60 hours, provided they don't exceed 152 knots or -0/+2.5 Gs, don't fly aerobatics, avoid flight into known moderate or severe turbulence, and complete a surface eddy current inspection. It applies to aircraft that have had wing spar modifications by GAMI, Nogle & Black, or Parks Industries. Owners need to contact the original AMOC holder to get the 60-hour flight extension.

Those aircraft modified by the Saunders Strap AMOC must complete the same surface eddy current inspection as the other AMOCs. However, once the inspection is completed, the airplane is returned to its original flight envelope and has a 300-hour interval between inspections of the center section.

The importance to our members:

The FAA's Emergency AD 2004-25-51 grounds all T-34s until they can be inspected or modified under a program approved by the Wichita Aircraft Certification Office. However, investigators do not know yet exactly what caused the left wing to fail, so there is no approved inspection program; therefore, the T-34s are effectively grounded for an indefinite period. The AD does allow owners to fly their aircraft back to home base or to a maintenance facility. For that purpose, owners may fly the aircraft for up to 10 hours within the next 30 days, provided they do so in VFR conditions, do not exceed 152 knots, and do not impose any loads on the aircraft greater than Normal-category flight (-0 to +2.5 G).

Most recent Web posting:

T-34s can fly again - for a while

The FAA has issued several "alternate means of compliance" (AMOC) that will allow most T-34s to get back in the air this summer. And there is a special AMOC for airshow performer Julie Clark that will permit her to fly at least some of her performances this season. The T-34 Association worked closely with the FAA to obtain this solution, while AOPA assisted by working with both groups.

The Beechcraft T-34 Mentors, former military training aircraft similar to the Bonanza, were grounded late last year following the third in-flight breakup of a T-34 used in mock aerial combat. (See " AOPA advocates for owners of aging aircraft.")

The new AMOCs will allow most owners to fly their T-34s for up to 60 hours, provided they don't exceed 152 knots or -0/+2.5 Gs, don't fly aerobatics, avoid flight into known moderate or severe turbulence, and complete a surface eddy current inspection. It applies to aircraft that have had wing spar modifications by GAMI, Nogle & Black, or Parks Industries. Owners need to contact the original AMOC holder to get the 60-hour flight extension.

Those aircraft modified by the Saunders Strap AMOC must complete the same surface eddy current inspection as the other AMOCs. However, once the inspection is completed, the airplane is returned to its original flight envelope and has a 300-hour interval between inspections of the center section.

For more information, contact the T-34 Association.

Significant provisions:

Emergency AD 2004-25-51

  • Issued December 10, 2004, and is effective immediately upon receipt.
  • This AD affects Beech Models 45 (YT-34), A45 (T-34A, B-45), and D45 (T-34B) airplanes, all serial numbers that are certificated in any category.
  • This AD is the result of cracks found in a location that was previously inspected and found to comply with AD 2001-13-18 R1, and two new locations.
  • Issued to detect and correct cracking in the wing structure of the affected airplanes, which could result in the wing separating from the airplane with consequent loss of control of the airplane.
  • AD requires you to perform an inspection and/or modification program approved specifically for this AD by the FAA Wichita Aircraft Certification Office (ACO) prior to further flight after the receipt.
  • You may operate the airplane up to 10 hours time-in-service (TIS) provided the flight(s) occur(s) no later than 30 days after receipt of this emergency AD to return/position the airplane to a home base, hangar, maintenance facility, etc.
    During the time allowed before compliance with paragraph (e)(1) of this AD or for any approved special flight permit, you must adhere to the following limitations:
    1. NEVER EXCEED SPEED, V NE - 175 MPH (152 knots);
    2. NORMAL ACCELERATION (G) LIMITS - 0, and +2.5;
    3. ACROBATIC MANEUVERS PROHIBITED.
    4. FLIGHT INTO KNOWN OR FORECAST MODERATE OR SEVERE TURBULENCE IS PROHIBITED.
    5. DAY VISUAL FLIGHT RULES (VFR) OPERATION ONLY.
    6. PILOT AND ANY ADDITIONAL FLIGHT CREW MEMBER REQUIRED FOR SAFE OPERATION.
  • Special flight permits are allowed for this AD.
  • To help in the long-term airworthiness solution for the safety and continued airworthiness of these airplanes, FAA is requesting data from every owner/operator on the following on these airplanes: (i) Service/Repair History (cracked/fatigued structure); (ii) Maintenance Schedule; and (iii) Total Hours Time-In-Service (TIS). Send to Paul Nguyen, Aerospace Engineer, FAA, Wichita Aircraft Certification Office, 1801 Airport Road, Mid-Continent Airport, Wichita, Kansas 67209; telephone: 316/946-4125; facsimile: 316/946-4107; e-mail: paul.nguyen@faa.gov.

Revision of AD 2001-13-18

  • AD becomes effective on March 15, 2004.
  • AD supersedes AD-99-12-02 and mandates the initial and repetitive inspections spelled out in Raytheon's mandatory service bulletin SB-57-3329. If cracks are found, the AD mandates wing spar replacement.
  • AD rescinds all four approved alternate methods of compliance (AMOCs)
  • Requires all T-34s that have accumulated 80 hours time in service since the original AD was issued in August 2001 to comply with Raytheon Service Bulletin SB57-3329 for additional inspections.

Airworthiness Concern Sheet

  • On December 22, 2003, the FAA issued an Airworthiness Concern Sheet (ACS) on Beech T-34 aircraft to AOPA and type clubs.
  • ACS proposes an additional inspection of two fatigue locations on T-34s in addition to existing AD 2001-13-18.
  • On December 31, 2003, the FAA issued Flight Standards Information Bulletin FSAW 03-11, titled Special Inspection for T-34 Mentor Aircraft.
  • "This bulletin provides guidance to Flight Standards District Offices (FSDO) in order to perform a special inspection on operators of T-34 aircraft. The special inspection is divided into two operating categories. Category 1 pertains to T-34 aircraft used in high 'G' operations such as Air Combat and Upset training. Category 2 pertains to other low 'G' operations such as military flying clubs, partnerships, and privately owned aircraft used In Title 14 of the Code of Federal Regulations (14 CFR) part 91 operations."
  • "Within 30 days of the effective date of this FSAW, inspect all Category 1 operators of T-34 aircraft offering air combat and upset training to the public for current annual/100 hours inspections, AD compliance (especially AD 2001-13-18 or its AMOC), and general airworthiness condition. Within 120 days of the effective date of this FSAW, inspect all Category 2 operators of T-34 aircraft for compliance with annual / 100 hour inspections, compliance with all ADs (especially AD 2001-13-18, or its AMOC), and general airworthiness condition."

Raytheon Aircraft Corporation Mandatory SB 57-3329 and AD 2001-13-18

  • Citing the existence of fatigue cracks in the wing spars of the accident airplane, Raytheon has issued "mandatory" SB 57-3329 calling for an exhaustive initial inspection and repetitive wing spar inspection at 80-hour intervals.
  • The FAA estimates that the initial inspection will cost $14,460 per airplane, and each repetitive inspection will cost nearly $1,900.
  • Raytheon has refused to produce replacement wing spars. Some aircraft may be retrofitted with Beech 55 or 58 series wing spars through STC. Such a replacement would cost over $14,000.
  • Although Raytheon's service bulletin recommends that the wing spar inspections be completed prior to further flight, the final AD allows up to 80 hours TIS or 1 year (whichever occurs later) to conduct the initial inspections.
  • FAA approved alternative means of compliance (AMOC) include a Nogle and Black front wing spar replacement, Aviadesign, Inc. inspection and spar strap, and a T-34 Association rear bathtub fitting fluorescent inspection procedure.
  • SAIB CE-02-08 lists approved AMOCs and provides means to extend the compliance deadline of AD 2001-13-18
  • SAIB CE-02-08 extends the AD compliance deadline by 200 hours TIS or 24 months, whichever occurs first, provided owners adhere to operational limitations and inspect the rear spar attach fitting for cracks.
  • SAIB CE-02-08 requires inspection of the rear spar attach fitting via the FAA approved T-34 Association fluorescent inspection procedure. If inspection reveals no cracks, owners may continue operation under the operational limitations listed in AD 2001-13-08 while they await completion of an approved AMOC.
  • Owners must schedule a time for completion of an AMOC to utilize the extended AD compliance deadline. Details are included in the SAIB attached below.

AOPA position:

AOPA is concerned with this latest accident and how it will affect the future of T-34 aircraft. On a larger scale, we are also concerned with how this accident will affect the FAA's overall views on aging aircraft. As with most issues, a myriad of mitigating factors may have led to this most recent wing failure and will impact the actions taken by the FAA and the T-34 community. AOPA will continue to work closely with the FAA and the affected industry to explore viable solutions that adequately address the safety concerns.

Status:

  • April 19, 2005, the FAA has issued several "alternate means of compliance" (AMOC) that will allow most T-34s to get back in the air this summer. The new AMOCs will allow most owners to fly their T-34s for up to 60 hours, provided they don't exceed 152 knots or -0/+2.5 Gs, don't fly aerobatics, avoid flight into known moderate or severe turbulence, and complete a surface eddy current inspection. It applies to aircraft that have had wing spar modifications by GAMI, Nogle & Black, or Parks Industries. Owners need to contact the original AMOC holder to get the 60-hour flight extension. Those aircraft modified by the Saunders Strap AMOC must complete the same surface eddy current inspection as the other AMOCs. However, once the inspection is completed, the airplane is returned to its original flight envelope and has a 300-hour interval between inspections of the center section.
  • March 7, 2005, the FAA issued Special Airworthiness Information Bulletin (SAIB) CE-05-36 to alert T-34 owners of an approved inspection program for airplanes that have not yet reached 3,800 hours total time in service (TIS).
  • February 25, 2005: T-34 Public Meeting Presentations
  • January 18, 2005, the FAA announces a public meeting of interest to owners and operators of Raytheon Aircraft Company (Raytheon) Beech Models 45 (YT-34), A45 (T-34A, B-45), and D45 (T-34B) airplanes. The purpose of the meeting is to discuss technical issues and potential corrective actions related to the continued operational safety of the affected airplanes, specifically related to the structural fatigue of critical structure and Airworthiness Directive (AD) 2004-25-51.
  • December 10, 2004, the FAA publishes Emergency AD 2004-25-51 effectively grounding fleet.
  • March 1, 2004, the FAA publishes revision to AD 2001-13-18.
  • December 31, 2003, AOPA responds to FAA's Airworthiness Concern Sheet.
  • December 31, 2003, the FAA issued Flight Standards Information Bulletin FSAW 03-11 titled Special Inspection For T-34 Mentor Aircraft.
  • December 22, 2003, the FAA issued an Airworthiness Concern Sheet (ACS) on Beech T-34 aircraft to AOPA and type clubs.
  • July 2, 2001, the FAA issued final AD 2001-13-18.
  • July 5, 2000, the FAA extended the comment period to October 15, 2000.
  • May 5, 2000, the FAA issued proposed AD 2000-CE-09-AD.
  • February 2000, Raytheon issued "mandatory" SB 57-3329.
  • On June 14, 1999, the FAA issued AD 99-12-02.

Related documents:


Updated Friday, April 22, 2005 4:09:37 PM