I agree with Rutan: It’s amazing how the word ‘safety’ can turn some people into gibbering idiots.
I’ve posted this in the threads about DAMP and the proposed SS terminal AD, but it’s about this ECi Cylinder AD. Well known expert and aviation journalist Mike Busch said this, in part, in response to the NPRM for the AD:
On August 12, 2013, the FAA published a Notice of Proposed Rulemaking (NPRM) in the Federal Register for a proposed Airworthiness Directive (AD) that would basically legislate more than 30,000 ECi cylinders out of existence, forcing the owners of about 6,000 Continental IO-520, TSIO-520 and IO-550 engines to perform $14,000 top overhauls. The total cost to affected aircraft owners would be $83 million, making this one of the most costly general aviation ADs in history. The FAA’s rationale for this Draconian AD is that they’ve received reports of 30 head-to-barrel separations in ECi cylinders (out of a population of 30,000, a failure rate of 0.1%).
This proposed AD is one of the most unwarranted, inappropriate, punitive and generally boneheaded rulemaking actions I’ve ever seen come from the FAA. Here’s why:
- At 0.1%, the reported head separation rate of ECi cylinders is the lowest in the industry, lower than for Continental factory cylinders. Why is the FAA picking on ECi jugs?
- There have been ZERO accidents and ZERO injuries resulting from the reported head separations of ECi cylinders.
…
My all-time favourite comment on this proposed AD (and any other one for that matter) is:
I am an emergency physician of 35 years experience with extensive involvement in helicopter EMS and a private pilot flying in the back country of Idaho. I understand, in detail, risk mitigation.
I wish to point out that based on available information the risk of appendicitis in FAA employees is much higher than having a ECI cylinder fail inflight. Following the FAA's assessment model, immediate prophylactic appendectomy is indicated for all 47,000 FAA employees.
Immediate appendectomy is particularly indicated for the 30,000 FAA employees involved air traffic control, as an appendix "failure" while on duty can affect the lives of hundreds people inflight.
I can provide the supporting calculations if desired.
You see, yr right, if the probabilities and consequences of ECi cylinder failures justify this AD, it follows that other risks with similar probabilities and similar consequences must justify similar regulatory action.
For example, people with learning difficulties should be prohibited from conducting maintenance on aircraft. Even though there may have been zero accidents and zero injuries from their activities, they
could cause a big accident by misunderstanding some important maintenance data. All in the interests of ‘safety’, old boy. Surely it’s a cost you’d be willing to pay? I’d be amazed if you disagreed.
Have been considering Walter's bait
Without the screw thread the head would depart on the first runup
It is a combination of the screw thread and interference fit that retains and locks the head to the cylinder
Is that your guess, No Hoper, or a conclusion supported by data?