NTSB Supports Less Draconian ECi Cylinder AD
November 14, 2013 - The NTSB has filed comments on a proposed AD that would require thousands of ECi cylinders on big-bore Continental engines to be retired from service before the end of their normal life. The NTSB told the FAA in its comments that the board has no data to support the proposed requirement that thousands of ECi cylinders with fewer than 500 hours' or more than 1,000 hours' time in service be removed.
The NTSB points out in its comments that the board has investigated and studied the failure history of ECi cylinders for many years. The NTSB issued a safety recommendation in February of this year that ECi cylinders produced between May 2003 and October 2009 be retired once the cylinders reach their normal recommended TBO life.
The proposed FAA AD, and the NTSB's research, divide affected ECi cylinders into two groups based on serial number. The NTSB notes that Group A cylinders are already flying under an ECi mandatory service bulletin that demands repetitive inspections for cracks every 50 flight hours after the cylinder accumulates 500 hours. The NTSB commented that cylinder head cracking in this group of cylinders could cause loss of compression but is unlikely to result in a cylinder head-to-barrel separation.
The NTSB also comments that cylinders in Group B should have repetitive inspection but does not believe there is any safety benefit to be gained by removing the cylinders before their normal recommended TBO is reached.
The bottom line is that the FAA's proposed AD would affect many more cylinders than NTSB testing and data collection indicates is necessary. The NTSB calls on the FAA to provide any new or additional data that could support expanding the cylinder action as proposed in the AD.
It is very unusual for the FAA to be calling for more expansive action than the NTSB. The FAA has yet to provide data to support these proposed actions. And the NTSB comments on the AD fall largely in line with the general aviation industry that has been unable to find sufficient data and safety reasons to retire thousands of cylinders early at a cost of millions of dollars to airplane owners.
Read the full NTSB comments on the proposed ECi AD.