Asking the Wrong People
I read with interest your article on EMS operations ("Accidents, Billing Top EMS Priorities," February 2005, page 42). As a long-time subscriber and pilot of 22 years (10 of them in EMS), I feel I should make a few points that may prove interesting for future articles on this subject.
While I realize that the Assn. of Air Medical Services (AAMS) has collected some data on numbers of EMS programs, helicopters, accidents, and some breakdowns of those, I noticed it only took four or so paragraphs to begin discussing reimbursement and billing. While I recognize that this plays a partial role in the competition among aeromedical programs, and may indirectly affect pressure on pilots, I fail to see how this directly affects safety (or should) and EMS operations.
Most average aeromedical pilots do not concern themselves with reimbursement rates, number of patient transports, or accounts receivable. So how does this concern become any type of factor in safety, and or accident rates? I know exactly how, as most of my colleagues do. Most pilots I have spoken with have the same feelings, and the same questions:
Why hasn't any organization asked the pilots what they feel are the root causes of this horrific accident rate? I find it at least an oblique conflict of interest that the organization that has a primarily aeromedical transport concern is discussing accident causal factors. Part of the safety issue may include the pressure pilots perceive from hospitals, administrators and medical directors to accept flights or compete with other programs for the transport of the patient.
Why do operators contribute a majority of input, with the realities of business clearly at the forefront of Part 135 operators' concerns in this climate of heightened competition, while pilots' concerns, input, and positions are conspicuously absent?
My fellow aeromedical pilots are as saddened, dismayed and horrified by the current aeromedical industry accident rate. We are losing our friends, co-workers and reputation with each and every accident. We see the increased emphasis on safety programs, safety and advisory councils, safety audits, etc. We know best the pressures on the average pilot--we live it every day we work and fly. The organizations (and operators) thus far are very concerned with EMS' safety record. But each organization's agenda is tempered by its main goals (be they transporting as many patients as safely possible, increasing revenue, or defending a market niche). The average EMS pilot's main goals and agenda are simply to transport patients safely, without an accident.
We aeromedical pilots know what we are facing, and we know what is happening in this industry and at our own programs. Why not solicit our opinions once in a while? Why not let us have a say in what the real causes of these accidents are?
AS350 Hydraulics Failures
I would like to comment on Tim McAdam's recent column ("AS350 Hydraulic Failures," February 2005, page 68). There is, in my opinion, a problem with the last paragraph of this article.
I fully agree with the statement that "a complete understanding of ... proper emergency techniques is extremely important to safe operations." However, I wish Mr. McAdams had asked an experienced AS350 pilot with experience performing the maneuver in question for his opinion, or preferably had flown the procedure himself, or even read the flight manual, rather than using whatever other source he did in coming up with the next statement: "Moreover, pilots should keep in mind that without hydraulic boost the collective moves down. Letting go of that control in a hover will cause the helicopter to quickly hit the ground" (emphasis added).
It is impossible for the collective to bottom out by itself without hydraulic boost. Without hydraulic boost, the collective force will be zero at the point where the spherical stops in the rotor head are neutral (+7 deg. pitch) which, in forward flight, equals a speed in the range of 40-60 kt. At this speed, there will be no force required on the collective to maintain its position to stay at that speed. To go faster or slower from that speed will require more collective force, the force required increasing to up to 25-30 lb. to get the aircraft up to 120 kt. and from a hover, up to 25-30 lb. down force to lower the collective fully to flat pitch. For any pitch position above or below +7 deg., the force required on the collective increases with more or less pitch.
The bottom line is letting go of the collective in a hover will not cause the helicopter "to quickly hit the ground." In fact, letting go of the collective will cause it to move to a position corresponding to the +7-deg. pitch position, and will require a downward force on the collective to land it from the hover.
Chief Test Pilot
Eurocopter Canada Limited
Tim McAdams responds: I agree with Mr. Krebs' technical description of the hydraulic system. However, what remains questionable is whether the collective moving to the neutral point in the spherical stops will allow the helicopter to maintain a hover. In writing this column, I asked a CFI that regularly provided training in the AS350 that very question. His response was that, in all but ideal conditions (i.e.... lightly loaded, dense air, headwind etc.), the collective required constant up force to maintain a hover. This seems consistent with Mr. Krebs' statement that the neutral-force point equates to an in-flight speed of 40-60 kt. Normally, helicopters require more power and, therefore, more collective pitch to maintain a hover than to cruise at 40-60 kt.
It is also worth noting that in a controlled training environment a pilot might be able to let go of the collective control without contacting the ground. However, based on conversations with AS350 pilots, I believe that in a real emergency with a heavily loaded helicopter and less than ideal conditions that the helicopter will hit the ground if the collective is released. How quickly it happens depends on the conditions.
I appreciate Mr. Krebs comments and attention to this issue. Generating dialog raises awareness and that will only enhance safety. In fact, I would like to hear comments and experiences from other pilots regarding hydraulic off maneuvers in the AS350.